Difference between revisions of "LaTeX/C2/Equations/English"

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'''You are here''': [[Main Page]] >> [[Spoken Tutorial Processes]] >> [[LaTeX]] >> Equations
 
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----
 
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Welcome to this tutorial on creating equations through latex. You see three windows as usual. I have created a 12pt size, article class document. And using AMSmath package and also using the ccliscences package for creative common copyright statement as here. Make title, creates the title page. New page command, takes the rest of the document to a new page.
 
−
There are many ways to create equations, I will use the command align star to create equations. Let us begin with a matrix differential equation consisting of four components. Align star, Frac ,d by dt of begin b-matrix, x_1, next line, x_2,end b-matrix. Let me close this. Let us compile it. So we have created ‘d by dt of x1 x2’.
 
  
−
Let us now augment the vector with two more components. You do it as follows. Next line x3, next line x4. Save it. Compile it. So I have four components. Let me now say that this is equal to the right hand side matrix of begin b-matrix. Zero, zero, one, zero. Next line:  zero, zero, zero, one. And then, lets close this matrix. Save. So I have this.  
+
{| border = 1
−
So I have written the first two rows. It is always a good idea to compile after very few small additions so that we have not made a mistake. Note that the align star environment takes the role of the dollar signs. For example, we did not enter the dollar sign at all. As a matter of fact, we should not enter the dollar sign within the aligned star environment.  
+
|-
 +
|| Initial conditions
 +
||
 +
# Copy equations.tex into numbers.tex
 +
# Both equations.tex and numbers.tex should be sized
 +
# Both should be opened in TeXworks
 +
# Both should be at the first line
 +
# equations.tex should be at the top, and numbers.tex should be below
 +
# Compile numbers.tex and get numbers.pdf
 +
# numbers.pdf should be sized
 +
# numbers.pdf should be scrolled all the way to the top
 +
# eqn-slides.pdf should be at the first slide
 +
# All should be arranged, as recorded in the tutorial
 +
# equations.tex should be directly below the slides file
 +
|-
 +
|| TeXworks: Lucida
 +
|| Grande, 22pt, 20px. Preview: 75%, 200dpi
 +
|-
 +
|}
 +
<br>
 +
<br>
  
−
Let us add a third line to the matrix on the right hand side and illustrate this idea. Zero, dollar minus gamma, zero, zero. So there are four entries. Compile it. It comes and says, missing dollar inserted. What we will do is, lets come here, get rid of these dollar signs. Save it. Exit compilation by this x. recompile it and note that minus gamma has come. So we need one more line here, we put that. Zero, alpha without dollar sign, zero, zero. Alright, now this is the way to do that.
+
{| border = 1
−
Lets complete this equation. I have a few more terms here. Let me just see if it is here, yes it is here. Let’s cut this. Put this here. Let’s see what happens when I compile this.  This is a model of an inverted pendulum.
+
|-
−
What do you do when you have more than one equation?  Let us add one more aligned statement. And I have written this equation here. Let me bring it from there. Here is the equation, so let me say begin align star. Let’s cut this. Copy this. Close this align. We compile it. When I compile it, I get the second equation appearing.  
+
||'''Visual Cue'''
 +
||'''Narration'''
 +
|-
 +
|| Opening slide
 +
|| Welcome to this tutorial on writing equations using '''LaTeX'''.
  
−
There are two problems with this. There is a large gap between the two equations and also we may want to align the equations. In view of these observations, we put both of these equations into a single align star environment. So we will do this as follows. Delete this. Save this. Compile it. Now what has happened is that both the equations have come on the same line. We will take care of that by telling latex to split this by the reverse slash.  Two of them. When I compile it, now these have gone to second equation.  But the equations are not aligned.  Suppose we want to align the equal to sign. Suppose we want to align these two signs, we put an ampersand symbol in front of the equal to signs here. Lets put it. And then we will put it here also. Ampersand. Let’s compile this. Now notice that both of them are aligned.  
+
My name is Kannan Moudgalya.
 +
|-
 +
|| Learning objectives slide
  
−
Suppose we want to introduce some text in between the equations without upsetting the alignment. This can be achieved using the inter-text command.  So we remove, we made a mistake here, the delta mu has come here. So what we should do is, let us first, put this properly, compile this. Now delta mu has come there. U of t is here. Now we want introduce some text between these two. So the line separator slash, slash is removed and that place we introduce this text that we want to include. Let’s take this text  and put it there. Whatever text we want to put appears in braces with an inter-text command. Note that the opening brace has to be closed, not closing the brace is a common mistake made by the beginners. Lets compile this.  So here is the text and you also have the equations aligned. Note also the use of the dollar sign within the inter-text command. Inter-text is like running text, so this is not part of the align environment. You need to include dollars here.
+
Down arrow
  
−
These equations don’t have numbers. In fact, the star in the aligned star command has told latex not to put the equation numbers. Let us remove the star and see what the aligned environment does. Let’s remove the star here. Also remove the star here. Let’s see what happens. So equation numbers have appeared automatically. We want to refer to them, so for example, let’s say we want to refer to them, so I have this here. Suppose this is the second equation I want to discretize, So I write this statement. Let me take this here, below this, put it.  Let me compile it. So it says we will now discretize the PID controller given in equation 2.  The equation numbers unfortunately may change while insertion or deletion of equations.
+
Down arrow
  
−
To demonstrate this, let us suppose, we include an equation here. Slash, slash, A equals B. And then we will delete these lines. Let’s compile this. Now I have A equals B as the second equation. Now this has become the third equation. Here we have hardcoded that equation 2 has to be discretized but this is no longer the second equation. Hardcoding of equation numbers in referencing always has this problem. This is solved by the label command. So let us come here and here at the end of the equation we introduce ‘label equation PID’ and then here I write in equation ‘ref’, ref is the command, and whatever than comes here label, should appear here also,  again within the braces,’ equation PID’. Lets see what happens when I compile it. 
+
Down arrow
−
On compiling it, we see question marks here.  On second compilation see what happens here – now it has become three. On second compilation the numbers become correct. This is similar to what we saw in table of contents. Let us now delete the A equals B equation. Let us get rid of this also.  Let’s compile it. This equation 2 is gone, but you still have this three. ON first compilation the reference gives the previous number, on second compilation the numbers become correct. The labels are case sensitive. For example, here I have called it equation PID, PID is in capitals. Let’s change this to small PID. What happens now,  here it says that it doesn’t know that. Its only that these have to be identical, these need not be characters.  For example, suppose I want to give numbers here, let me just put hundred, let me put 100. Save it. Compile it. Okay, it doesn’t know it yet in the first compilation, but if I compile it a second time it will know. Numbers are the same.  
+
|| In this tutorial, we will learn
 +
*How to create an equation in '''LaTeX'''.
  
−
In a similar way we can create labels for sections, sub-sections and so on. So let us do that, let us demonstrate this with section. Let us do it here. Section, this is first section. Label, sec 100. Then we go to the end of the document here. And says section ref sec-100, shows how to write equations. Save it. ‘Section, question marks shows how to write equations’. On next compilation this is taken care of. So section 1, this number is the same as this one. So this works for sections, sub-sections and so on. In fact with any environment that has a number associated with it. Alright, let’s delete these. Lets compile these. Once again. Alright.
+
*How to write multiple equations
  
−
We will now see how to accommodate long equations. So I have already written it here. Let me just go there at the end of the document, okay here it is.  Let me add this.  Put it here. Lets see what happens when I compile it.  So I have a third equation that I have added here, it’s a long equation. It’s a long equation so it doesn’t fit into one line. So let us break it into two. The way to do that is, let us break it here, slash, slash, and come here and I’m putting an aligned with this ampersand. Let me save it, Compile it. See that this equation has been broken into two parts and I am aligning it with the plus sign. All these equal signs and plus signs are aligned now.  Unfortunately we have equation numbers in both parts. Supposing we don’t want the number in the first line, suppose we don’t want this number. Include the command ‘no number’ before this slash, slash symbol. Do this as follows. Save this. Compile this. See that this equation number is gone and this has become three.
+
*How to align multiple equations and
−
We see that the braces we wanted in some terms are missing. For example here I have said E N, E N minus 1. Here it appears without these braces. This is because, braces are delimiters in latex. We now want to tell latex to not interpret these braces. This is done by putting a reverse slash before the braces. Let me put a reverse slash here. Let me also put a reverse slash here. See that we have the braces here similarly lets put it here also. Here and here. Save this, now we have got that.   
+
−
We will now show to create large graphics in equations. For example here, these brackets are very small. The way to do that is using – what are known as left and right commands.  So lets come here – so the equation is here. The way to do this is – K slash left and on this side I have this, so here I put slash right. Let’s compile this. See this, it has become bigger. We can do this also with square brackets. I got square brackets. I can also put braces, only thing is that I have to tell latex not to interpret. So I put a slash brace. Let’s compile this. See this braces.
+
  
−
When we have one equation split into multiple lines, we will have to put only the left on the first. For example, we have a bracket here and a bracket here, I want to make this slightly bigger. So let me do that here. Suppose for example, I want to put a left bracket here and here I want to put a right bracket. Compile it. It comes and complains ‘forgotten right’, because I opened it here but I didn’t close it in the same equation. The way to do that is to use what is known as slash right dot, that means don’t worry about the right hand side. Similarly , here we have to say slash left dot, don’t worry about the left here. Let me exit here. Let me re-compile it. So this is taken care of.  
+
*Why we should avoid the '''dollar mode''' and blank lines while writing equations
 +
|-
 +
|| System requirements slide
 +
|| One may use any of '''Linux, Windows''' or the '''Mac''' operating system.
  
−
Now suppose I want to push this a little inside. I can always says slash h-space 1cm. let me just do that shift. So this has been shifted, this has been aligned. If you don’t want this, you want the plus sign to come inside. Let’s do this here, put the plus sign here. Okay, this plus is now inside. Now this is nicely done. 
+
One needs '''LaTeX'''.
  
−
All commands that work in between the dollar sign also work between the aligned environment but for the ampersand symbol that is used for the aligning of multiple symbols. All commands that work in the aligned environment also work within the dollar symbols. Nevertheless, there is a small difference in the way some outputs appear in the aligned environment and in the running mode obtained with the dollar. This can be illustrated with the integral mode. So lets come here. Let’s delete this. So I have this statement here.  Let me take this, let me put it here. The integral mode includes the term this integral. Let me close this otherwise alignment will complain.  So what I have done is the integral mode includes the term this integral. Note the size of this integral size and this integral. This is a lot bigger and this is smaller.  
+
I shall use '''TexWorks''', although it is not required.
 +
|-
 +
|| Prerequisites slide
  
−
Such changes also occur in the case of fractions, sum and product to cite a few. There is one other thing that I want to tell before completing this tutorial. Aligned environment does not like blank lines in between. Suppose for example, I create a blank line here. It comes and says that paragraph ended before alignment was complete. If you really want a space, leave a percentage which tells latex that it is not common. Re-compiling.  It goes through and you get all the text as before.  
+
Press Down arrow
−
This brings us to the end of this tutorial. Thanks for listening. This is Kannan Moudgalya signing off. Good-bye.
+
 
 +
Down arrow
 +
|| What are the prerequisites?
 +
 
 +
One needs to be familiar with spoken tutorials that introduce '''LaTeX'''.
 +
 
 +
Exposure to the recommended method of '''side-by-side learning'''.
 +
 
 +
This information is available at the '''Spoken Tutorial''' webpage.
 +
|-
 +
|| Additional material slide
 +
|| I shall use the file '''equations.tex'''
 +
 
 +
|-
 +
||Open in TeXworks
 +
||I have opened it in '''TeXworks'''.
 +
 
 +
|-
 +
||Back to slides file, press down arrow
 +
 
 +
Press down arrow
 +
 
 +
Press down arrow
 +
||It is available as a code file along with this tutorial.
 +
 
 +
You need to have it to practise along with me.
 +
 
 +
If you don't have it, please download it from the '''Spoken Tutorial webpage'''.
 +
|-
 +
|| Slide on Leslie Lamport’s book
 +
 
 +
 
 +
|| I will next call your attention to this standard textbook by '''Leslie Lamport'''.
 +
 
 +
I learnt my '''LaTeX''' from this book.
 +
 
 +
It is available for about Rs. 500.
 +
 
 +
|-
 +
||Web browser is opened
 +
||Let me show on the web browser where one can buy it.
 +
 
 +
|-
 +
||
 +
|| Let us begin this tutorial
 +
|-
 +
|| Open equations.tex
 +
 
 +
 
 +
|| Let us learn how to write equations using '''LaTeX'''.
 +
 
 +
I have already opened the file '''equations.tex''' in '''TeXworks'''.
 +
 
 +
I have saved it as '''numbers.tex''' to use in this tutorial.
 +
 
 +
I will keep the file '''equations.tex''' intact, and not change it.
 +
 
 +
|-
 +
||Open numbers.tex
 +
||Let me open '''numbers.tex'''
 +
 
 +
|-
 +
||
 +
||Please pause the tutorial, make this copy and open it.
 +
 
 +
Whenever you want to start afresh, you can make a new copy of '''equations.tex'''
 +
 
 +
I recommend this method whenever a code file is given with ANY spoken tutorial.
 +
|-
 +
|| Press the '''Typeset''' key
 +
|| Let us '''compile''' this file by pressing the '''Typeset''' arrow at the top left hand corner.
 +
 
 +
|-
 +
||Pdf file
 +
||You can see the '''pdf file''' on the right.
 +
 
 +
|-
 +
||Switch to the tex file.
 +
||Let us look at the '''tex''' file, which begins with its usual '''commands'''.
 +
 
 +
|-
 +
||Highlight 8cm
 +
||I have chosen the width of the '''pdf file''' to be 8cm.
 +
 
 +
This is the only way I can show the entire file and also use a large font.
 +
|-
 +
||
 +
 
 +
Change 8 to 15
 +
 
 +
Put back 8
 +
 
 +
|| You may want to increase it to a more reasonable value, such as 15cm.
 +
 
 +
But I will continue to use 8cm.
 +
 
 +
|-
 +
||Click amsmath line
 +
||I am using the '''package amsmath'''.
 +
 
 +
|-
 +
|| Click the first align
 +
|| I write the first equation within the '''align star environment''', as shown here.
 +
 
 +
|-
 +
||Switch to the pdf and highlight the equation.
 +
||You can see how it gets '''typeset''' in the '''pdf file'''.
 +
 
 +
|-
 +
||Click u(t) line in tex
 +
||On the left hand side of this equation, we have '''u of t'''.
 +
 
 +
|-
 +
||Click u(t) in the pdf file
 +
||On the right hand side, I have produced big square brackets.
 +
 
 +
|-
 +
||
 +
 
 +
 
 +
Hover on \left and click \right
 +
||How did I do this?
 +
 
 +
With '''back slash left square''' and '''back slash right square''' brackets as shown here.
 +
|-
 +
|| Scroll the tex file up
 +
 
 +
 
 +
Click align* line
 +
|| Similarly, I write a second equation using '''align star'''.
 +
 
 +
|-
 +
||Click the x_1 line
 +
||On the left hand side, we have the '''derivative''' of a '''vector'''.
 +
 
 +
|-
 +
||Click on the eqn in the pdf file
 +
||We can see the '''pdf output''' here.
 +
 
 +
|-
 +
||Click on matrix tex
 +
|| On the right hand side, we have a '''3 by 3 matrix'''.
 +
 
 +
|-
 +
||Click on matrix pdf
 +
||See the corresponding output.
 +
 
 +
|-
 +
||Delete row 1 compile
 +
||Suppose we delete the first row in this '''matrix''' and '''compile'''.
 +
 
 +
|-
 +
||
 +
Click the pdf
 +
 
 +
 
 +
 
 +
||We get a '''2 by 3 matrix pdf output'''.
 +
 
 +
The first line is gone.
 +
 
 +
It is your responsibility to make the equations correct and consistent.
 +
 
 +
|-
 +
||Undo the last command in tex
 +
||Let me put the row back.
 +
 
 +
|-
 +
||Compile
 +
||Let me '''compile'''.
 +
 
 +
|-
 +
||
 +
||You can also add more rows, if necessary.
 +
 
 +
Similarly, you can change the columns, too.
 +
 
 +
|-
 +
||
 +
|| Recall that we used the '''dollar mode''' to write formulae in another tutorial.
 +
 
 +
|-
 +
||Click on '''begin align''' in tex
 +
||Here, '''align''' plays the role of the '''dollar mode'''.
 +
 
 +
In fact, one should not put the '''dollar sign''' within the '''align environment'''.
 +
 
 +
|-
 +
||Put $ and compile
 +
 
 +
 
 +
||Suppose we put the '''alpha symbol''' within '''$ signs''' and '''compile'''.
 +
 
 +
|-
 +
||Error message
 +
||We get an error message about '''dollar'''.
 +
 
 +
|-
 +
||Press red cross symbol to abort
 +
||Press the cross symbol on the top left red box and abort the previous '''compilation'''.
 +
 
 +
|-
 +
||Remove '''$ signs'''
 +
||Let us remove the '''dollar''' sign.
 +
 
 +
'''Compile''' again, it works!
 +
|-
 +
|| Below the line with alpha, leave a blank line
 +
 
 +
 
 +
 
 +
|| Another common mistake is leaving blank lines in the '''align environment'''.
 +
 
 +
Let me leave an empty line and '''compile'''.
 +
 
 +
|-
 +
||Error message
 +
||It gives an error message.
 +
 
 +
|-
 +
||Put %
 +
||If you need this gap, put '''%''', the '''comment''' character, in the first column.
 +
 
 +
|-
 +
||Press red cross symbol to abort
 +
||Abort '''compiling'''.
 +
 
 +
|-
 +
||Press Typeset symbol to compile
 +
||'''Compile''' again - it '''compiles ok'''.
 +
 
 +
So it is important to remember that you should not leave a blank line within the '''align statement'''.
 +
 
 +
|-
 +
||Remove the blank line
 +
||Let me remove this line and '''compile'''.
 +
 
 +
|-
 +
||
 +
||Next, I want to align the two equations by the '''equal to''' sign.
 +
 
 +
For this, we need to put both equations inside one '''align star environment'''.
 +
 
 +
|-
 +
|| Remove \end{align*}
 +
 
 +
Remove \begin{align*}
 +
|| Remove the end '''align* command''' of the first equation.
 +
 
 +
Remove the begin '''align* command''' of the second equation.
 +
 
 +
|-
 +
||Compile
 +
|| Let us '''compile'''.
 +
 
 +
|-
 +
||In the pdf file
 +
||We see only one equation appearing.
 +
 
 +
The text in between the two equations appears as a large string.
 +
 
 +
The second equation does not even show up.
 +
 
 +
|-
 +
||
 +
|| This is not what we wanted.
 +
 
 +
This problem is solved with the help of the '''intertext command'''.
 +
 
 +
|-
 +
||Add braces before and after the text.
 +
||Let us put the text in between braces.
 +
 
 +
|-
 +
||Put the text into \intertext{}
 +
 
 +
 
 +
 
 +
 
 +
||Let us also put this '''command, back slash intertext''' as I type now.
 +
 
 +
Note that '''intertext''' is one word, without a space in between.
 +
 
 +
|-
 +
||Point to the '''\'''
 +
||Do not forget the '''back slash''' before '''intertext'''.
 +
 
 +
|-
 +
||Point to the closing brace
 +
||Also, do not forget the closing brace.
 +
 
 +
These are all common mistakes.
 +
 
 +
|-
 +
||Compile
 +
 
 +
 
 +
 
 +
 
 +
 
 +
||On compiling, we get this '''pdf''' file.
 +
 
 +
You see both equations now.  But unfortunately, you see both the equations right aligned.
 +
 
 +
Not aligned by the '''equal to''' sign.
 +
 
 +
|-
 +
||
 +
||So, I am not happy with it.
 +
 
 +
I want to align by the '''equal to''' sign.
 +
 
 +
|-
 +
||Put & sign before =
 +
 
 +
||To do this, let us put the '''ampersand''' sign in front of the '''equal to''' sign.
 +
 
 +
Let's do it for the first equation.
 +
 
 +
|-
 +
||Repeat in the 2<sup>nd</sup> eqn.
 +
 
 +
 
 +
 
 +
||And then let's do it for the second equation.
 +
 
 +
If you have more equations to be aligned, do this for all of them.
 +
 
 +
|-
 +
||Compile
 +
||On '''compiling''', we see the two equations aligned by the '''equal to''' sign.
 +
|-
 +
||
 +
|| The equations are aligned even though there is text in between.
 +
 
 +
Remember to use the '''intertext command''' whether you want the equations aligned or not.
 +
|-
 +
||
 +
Delete text lines
 +
|| What do we do if we don’t have text between equations?
 +
 
 +
To understand this, let us delete the entire text between the two equations.
 +
 
 +
|-
 +
||Put \\
 +
||Note that we should not leave an empty line.
 +
 
 +
|-
 +
||Compile
 +
||On '''compiling''', we see both equations coming in the same line.
 +
 
 +
We didn’t tell '''LaTeX''' to start the second equation in the next line.
 +
 
 +
|-
 +
||Add '''\\'''
 +
||We solve this by putting two '''back slashes''' at the end of the first equation.
 +
 
 +
|-
 +
||Compile
 +
||Let us compile, to get the correct '''pdf''' file.
 +
 
 +
|-
 +
||Undo
 +
||Let us now undo and put the text in between two equations.
 +
 
 +
|-
 +
||Compile
 +
||Let us '''compile''' once more.
 +
|-
 +
||
 +
|| This is where we will stop.
 +
 
 +
Let me go to the slides.
 +
|-
 +
|| Summary slide
 +
 
 +
Down arrow
 +
 
 +
Down arrow
 +
|| This page summarises what we learnt in this tutorial.
 +
 
 +
Please recall each of these '''commands'''.
 +
 
 +
This is your first assignment.
 +
|-
 +
|| More assignments slide
 +
 
 +
Down arrow
 +
|| I will give some more assignments.
 +
 
 +
Can you pause the video and try to produce these equations?
 +
 
 +
The required code is given here.
 +
|-
 +
|| Assignment 3
 +
|| Can you produce these equations?
 +
 
 +
Notice that these equations are now aligned at the '''equal to''' sign.
 +
|-
 +
|| Assignment 4
 +
|| What happens if you forget a required '''ampersand''' sign?
 +
 
 +
Please pause the video and try this input.
 +
 
 +
You should get this output.
 +
 
 +
Forgetting '''ampersand''' signs is a common mistake made by everyone!
 +
|-
 +
|| Assignment 5
 +
|| Can you pause this video and try to produce this output?
 +
 
 +
Use the hint given here.
 +
|-
 +
|| Assignment 6
 +
|| In this assignment, you have to align three equations.
 +
 
 +
Please pause the video here, and try to produce them by yourself.
 +
 
 +
I have given the answer here.
 +
|-
 +
|| Assignment 7
 +
|| I have the last assignment in this slide.
 +
 
 +
Insert some text between equations.
 +
|-
 +
|| About the ST slide
 +
|| I will now give some general information.
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Latest revision as of 19:24, 22 October 2019

Initial conditions
  1. Copy equations.tex into numbers.tex
  2. Both equations.tex and numbers.tex should be sized
  3. Both should be opened in TeXworks
  4. Both should be at the first line
  5. equations.tex should be at the top, and numbers.tex should be below
  6. Compile numbers.tex and get numbers.pdf
  7. numbers.pdf should be sized
  8. numbers.pdf should be scrolled all the way to the top
  9. eqn-slides.pdf should be at the first slide
  10. All should be arranged, as recorded in the tutorial
  11. equations.tex should be directly below the slides file
TeXworks: Lucida Grande, 22pt, 20px. Preview: 75%, 200dpi



Visual Cue Narration
Opening slide Welcome to this tutorial on writing equations using LaTeX.

My name is Kannan Moudgalya.

Learning objectives slide

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In this tutorial, we will learn
  • How to create an equation in LaTeX.
  • How to write multiple equations
  • How to align multiple equations and
  • Why we should avoid the dollar mode and blank lines while writing equations
System requirements slide One may use any of Linux, Windows or the Mac operating system.

One needs LaTeX.

I shall use TexWorks, although it is not required.

Prerequisites slide

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What are the prerequisites?

One needs to be familiar with spoken tutorials that introduce LaTeX.

Exposure to the recommended method of side-by-side learning.

This information is available at the Spoken Tutorial webpage.

Additional material slide I shall use the file equations.tex
Open in TeXworks I have opened it in TeXworks.
Back to slides file, press down arrow

Press down arrow

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It is available as a code file along with this tutorial.

You need to have it to practise along with me.

If you don't have it, please download it from the Spoken Tutorial webpage.

Slide on Leslie Lamport’s book


I will next call your attention to this standard textbook by Leslie Lamport.

I learnt my LaTeX from this book.

It is available for about Rs. 500.

Web browser is opened Let me show on the web browser where one can buy it.
Let us begin this tutorial
Open equations.tex


Let us learn how to write equations using LaTeX.

I have already opened the file equations.tex in TeXworks.

I have saved it as numbers.tex to use in this tutorial.

I will keep the file equations.tex intact, and not change it.

Open numbers.tex Let me open numbers.tex
Please pause the tutorial, make this copy and open it.

Whenever you want to start afresh, you can make a new copy of equations.tex

I recommend this method whenever a code file is given with ANY spoken tutorial.

Press the Typeset key Let us compile this file by pressing the Typeset arrow at the top left hand corner.
Pdf file You can see the pdf file on the right.
Switch to the tex file. Let us look at the tex file, which begins with its usual commands.
Highlight 8cm I have chosen the width of the pdf file to be 8cm.

This is the only way I can show the entire file and also use a large font.

Change 8 to 15

Put back 8

You may want to increase it to a more reasonable value, such as 15cm.

But I will continue to use 8cm.

Click amsmath line I am using the package amsmath.
Click the first align I write the first equation within the align star environment, as shown here.
Switch to the pdf and highlight the equation. You can see how it gets typeset in the pdf file.
Click u(t) line in tex On the left hand side of this equation, we have u of t.
Click u(t) in the pdf file On the right hand side, I have produced big square brackets.


Hover on \left and click \right

How did I do this?

With back slash left square and back slash right square brackets as shown here.

Scroll the tex file up


Click align* line

Similarly, I write a second equation using align star.
Click the x_1 line On the left hand side, we have the derivative of a vector.
Click on the eqn in the pdf file We can see the pdf output here.
Click on matrix tex On the right hand side, we have a 3 by 3 matrix.
Click on matrix pdf See the corresponding output.
Delete row 1 compile Suppose we delete the first row in this matrix and compile.

Click the pdf


We get a 2 by 3 matrix pdf output.

The first line is gone.

It is your responsibility to make the equations correct and consistent.

Undo the last command in tex Let me put the row back.
Compile Let me compile.
You can also add more rows, if necessary.

Similarly, you can change the columns, too.

Recall that we used the dollar mode to write formulae in another tutorial.
Click on begin align in tex Here, align plays the role of the dollar mode.

In fact, one should not put the dollar sign within the align environment.

Put $ and compile


Suppose we put the alpha symbol within $ signs and compile.
Error message We get an error message about dollar.
Press red cross symbol to abort Press the cross symbol on the top left red box and abort the previous compilation.
Remove $ signs Let us remove the dollar sign.

Compile again, it works!

Below the line with alpha, leave a blank line


Another common mistake is leaving blank lines in the align environment.

Let me leave an empty line and compile.

Error message It gives an error message.
Put % If you need this gap, put %, the comment character, in the first column.
Press red cross symbol to abort Abort compiling.
Press Typeset symbol to compile Compile again - it compiles ok.

So it is important to remember that you should not leave a blank line within the align statement.

Remove the blank line Let me remove this line and compile.
Next, I want to align the two equations by the equal to sign.

For this, we need to put both equations inside one align star environment.

Remove \end{align*}

Remove \begin{align*}

Remove the end align* command of the first equation.

Remove the begin align* command of the second equation.

Compile Let us compile.
In the pdf file We see only one equation appearing.

The text in between the two equations appears as a large string.

The second equation does not even show up.

This is not what we wanted.

This problem is solved with the help of the intertext command.

Add braces before and after the text. Let us put the text in between braces.
Put the text into \intertext{}



Let us also put this command, back slash intertext as I type now.

Note that intertext is one word, without a space in between.

Point to the \ Do not forget the back slash before intertext.
Point to the closing brace Also, do not forget the closing brace.

These are all common mistakes.

Compile



On compiling, we get this pdf file.

You see both equations now. But unfortunately, you see both the equations right aligned.

Not aligned by the equal to sign.

So, I am not happy with it.

I want to align by the equal to sign.

Put & sign before = To do this, let us put the ampersand sign in front of the equal to sign.

Let's do it for the first equation.

Repeat in the 2nd eqn.


And then let's do it for the second equation.

If you have more equations to be aligned, do this for all of them.

Compile On compiling, we see the two equations aligned by the equal to sign.
The equations are aligned even though there is text in between.

Remember to use the intertext command whether you want the equations aligned or not.

Delete text lines

What do we do if we don’t have text between equations?

To understand this, let us delete the entire text between the two equations.

Put \\ Note that we should not leave an empty line.
Compile On compiling, we see both equations coming in the same line.

We didn’t tell LaTeX to start the second equation in the next line.

Add \\ We solve this by putting two back slashes at the end of the first equation.
Compile Let us compile, to get the correct pdf file.
Undo Let us now undo and put the text in between two equations.
Compile Let us compile once more.
This is where we will stop.

Let me go to the slides.

Summary slide

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This page summarises what we learnt in this tutorial.

Please recall each of these commands.

This is your first assignment.

More assignments slide

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I will give some more assignments.

Can you pause the video and try to produce these equations?

The required code is given here.

Assignment 3 Can you produce these equations?

Notice that these equations are now aligned at the equal to sign.

Assignment 4 What happens if you forget a required ampersand sign?

Please pause the video and try this input.

You should get this output.

Forgetting ampersand signs is a common mistake made by everyone!

Assignment 5 Can you pause this video and try to produce this output?

Use the hint given here.

Assignment 6 In this assignment, you have to align three equations.

Please pause the video here, and try to produce them by yourself.

I have given the answer here.

Assignment 7 I have the last assignment in this slide.

Insert some text between equations.

About the ST slide I will now give some general information.

This video summarises the Spoken Tutorial project.

Workshops slide We conduct workshops using Spoken Tutorials.
Answers slide

Press down arrow

Down arrow

Down arrow

Down arrow

Down arrow twice

Do you have questions in THIS Spoken Tutorial?
  • Please visit this site
  • Choose the minute and second where you have the question
  • Explain your question briefly
  • Someone from our team will answer them


You will have to register on this website to ask questions.

Where to post slide For topics not covered in spoken tutorials, visit stack exchange at this address.
Contact us slide For any other questions, please contact us.
Acknowledgement slide Spoken Tutorial project is funded by MHRD, Government of India.
Thanks for joining.

Goodbye.

Contributors and Content Editors

Chandrika, Nancyvarkey, Pravin1389

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