LaTeX/C2/Numbering-Equations/English-timed

Time	Narration
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.
03:21	Compile. 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. Goodbye.

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PoojaMoolya