|00:01|| Welcome to this tutorial on numbering equations using LaTeX.
My name is Kannan Moudgalya.
|00:09||In this tutorial, we will learn-|
|00:12||How to put equation numbers|
|00:15||How to remove them|
|00:17||How to correctly reference equations|
|00:21||How to use the information on the web|
|00:25||One may use any of Linux, Windows or a Mac operating system.|
|00:31||One needs LaTeX.|
|00:34||I shall use TeXworks.|
|00:37||What are the prerequisites?|
|00:39||One needs to be familiar with spoken tutorials that introduce LaTeX.|
|00:45||We recommend the use of the Side-by-Side method.|
|00:49||This information is available at the Spoken Tutorial webpage.|
|00:55||I shall use the following files:|
|00:58||numbers.tex, which you can see here.|
|01:03||ltxprimer pdf file from TUG India. It is here.|
|01:09||These are available as Code files along with this tutorial.|
|01:14||With these files, you will be able to practise along with me.|
|01:19||If you don't have these files, please download them from the Spoken Tutorial website.|
|01:26||Let us begin the tutorial.|
|01:28||Let us learn how to create numbers for equations in LaTeX.|
|01:33||I have already opened the file numbers.tex in TeXworks.|
|01:39||I have saved it as align.tex to use in this tutorial.|
|01:44||I will keep the numbers.tex file intact, and not change it.|
|01:49||Please pause the tutorial, make a copy of numbers.tex and open it.|
|01:55||Whenever you want to start afresh, you can make a new copy of numbers.tex|
|02:01||I recommend this method whenever a code file is given with ANY spoken tutorial.|
|02:08||Let me open align.tex|
|02:11||Let us compile this file by pressing the Typeset arrow at the top left hand corner.|
|02:18||You can see the pdf file on the right.|
|02:22||These equations do not have numbers.|
|02:26||We can put equation numbers by removing the star from the align star.|
|02:32||Let us remove the star from both begin and end statements.|
|02:39||Forgetting it in the end statement is a common mistake.|
|02:43||Let’s see what happens if I forget to remove it from the end align statement.|
|02:49||Let us compile.|
|02:51||It gives an error message begin align ended with align star.|
|02:57||Let us remove the star from end align also.|
|03:02||Let us abort typesetting and compile.|
|03:07||We now have equation numbers.|
|03:11||Let us now refer to the second equation in the running text.|
|03:16||Put the number 2 after the word equation.|
We see number 2 in the running text.
|03:27||I will now show you how to remove the equation number of one equation.|
|03:32||Suppose that we don’t want a number for the first equation.|
|03:37||Go to the end of the first equation, but before intertext, and put back slash nonumber.|
|03:46||Please note that nonumber is one word.|
|03:50||Do not forget the back slash at the beginning.|
|03:54||On compiling, the number disappears from the first equation.|
|04:00||One consequence is that the second equation is now numbered as one.|
|04:07||Unfortunately, the reference to the second equation has become wrong in the text.|
|04:13||Can we prevent such mistakes even if we have to add or remove equations?|
|04:19||Such a requirement occurs frequently while writing reports, theses, papers, etc.|
|04:27||It is possible to do this through the label statement.|
|04:32||We have seen this in a previous tutorial also.|
|04:36||Let me put slash label PID at the end of the second equation, but before end align.|
|04:47||Replace 2 in the running text with slash ref PID as I do now.|
|04:56||After compiling once, two question marks appear against the equation number.|
|05:02||On compiling twice, the question marks get replaced by the correct number.|
|05:09||Let us change the equation number once again by removing nonumber.|
|05:15||Compile twice to get correct answers.|
|05:20||The variable in the ref and label commands have to be identical.|
|05:26||Check what happens if you change PID in the ref command to lowercase.|
|05:34||Leave the PID in uppercase in the label command and compile.|
|05:40||We get question mark here because this lowercase pid is not defined.|
|05:48||I will put pid back in uppercase and compile.|
|05:55||I will now show you how to take help from the Internet.|
|06:00||Before that, I am going to delete everything in the tex file.|
|06:05||If you don’t like it, you can open a new file.|
|06:09|| To do this part, you need access to Internet.
If you don’t have this access now, you may try this part later.
|06:17||Let me go to a web browser.|
|06:20||Let me do a web search on the topic of LaTeX multiline.|
|06:27||The very first hit is on stackexchange.|
|06:32||Let me click this “How to align...”.|
|06:36||If you scroll down this page, you will see a question and several answers.|
|06:43||Most answers present a complete code.|
|06:48||Let us copy the code that says 58.|
|06:53||This number may be different when you access this page.|
|06:58||Below this, the pdf file created by this code is shown.|
|07:04||Let me paste it on the tex file.|
|07:08||Let us compile the tex file.|
|07:11||You can check the output in this pdf file to be identical to what we saw in stackexchange.|
|07:19||Please try all commands explained in this web page and understand them.|
|07:24||Next let me delete everything inside the document environment.|
|07:31||Let us now open the ltxprimer pdf file that we have provided with this tutorial.|
|07:38||You can practise this part even if you don’t have web access.|
|07:43||Let us scroll and go to Contents.|
|07:48||Let us click “Typesetting Mathematics”.|
|07:52||You can see many examples.|
|07:55||Let us go to page 87.|
|07:59||Let us copy “cases code” and paste it within the document environment.|
|08:08||On compiling it, we get the output given in ltxprimer.|
|08:14||You may change equation* to align*, and compile.|
|08:20||We get identical results.|
|08:23||I suggest that you spend a minute in understanding this example.|
|08:28||I also suggest that you try more examples from ltxprimer.|
|08:33||This brings us to the end of this tutorial.|
|08:37||This page summarises what we learnt in this tutorial.|
|08:42||Please recall each of these commands.
This is your first assignment.
|08:48||Please do a search on these commands over the web, in ltxprimer, etc.
Locate these examples and try them out.
|08:59||I will give some more assignments.|
|09:03|| We compiled twice to get correct numbers.
Why should we compile twice?
|09:09||Hint: we saw this in an earlier tutorial.|
|09:13||You can also locate an answer for this in ltxprimer.pdf file.|
|09:19||Search for Cross References.|
|09:22|| Try examples from Chapter 8 of ltxprimer pdf file we saw earlier.
Try to understand them.
|09:30||Try multiline examples from the Stackexchange web page we saw earlier.|
|09:36||I will now give some general information.|
|09:40||This video summarises the Spoken Tutorial project.|
|09:45||We conduct workshops using Spoken Tutorials.|
|09:50||Do you have questions in THIS Spoken Tutorial?|
|09:54||Please visit this site|
|09:56||Choose the minute and second where you have the question|
|10:00||Explain your question briefly|
|10:03||Someone from our team will answer them|
|10:06||You will have to register on this website to ask questions.|
|10:11||For topics not covered in spoken tutorials, visit stackexchange at this address.|
|10:17||This is a great place to get answers on LaTeX.|
|10:22|| You may also have questions on our workshops, certificates, etc.
For this, get in touch with us at this email address.
|10:32||Spoken Tutorial project is funded by MHRD, Government of India.|
|10:37|| Thanks for joining.