putting lines in multiline LaTex equations in the PDF version of an Rmarkdown file

[Erin Hodgess]

Good morning!

First of all, knitr, Rmarkdown, and Rstudio are the best things since sliced bread, Coca-Cola, etc.

I have one questions, which I'm sure is an easy fix.

I am making up some lecture notes for my students.  Some like HTML, while others prefer PDF.  I like happy students.  So I am using Rmarkdown within Rstudio. 

This is on a Mac, R Version 3.2.0.

Here are the lines from the Rmarkdown file:

We will review some of the very fun and interesting concepts that we discussed on Wednesday, August 26.

We know in our hearts that the gamma probability function is the following:

\[ 

f(x) = \dfrac{\lambda^r}{\Gamma(r)} x^{r-1} e^{-\lambda x}, 

\]

Here is some more stuff

\[

E[X] = \lambda \cdot \dfrac{\Gamma(2)}{\lambda^2}

 \left \lbrack \int_0^{\infty} \dfrac{\lambda^2}{\Gamma(2)} 

x e^{-\lambda x} \; dx \right \rbrack, \\

E[X] = \lambda \cdot \dfrac{\Gamma(2)}{\lambda^2} \cdot 1, \\

E[X] = \dfrac{(2-1)!}{\lambda} = \dfrac{1}{\lambda}

\]

This works just fine when I use knitr to HTML.  However, when I use knitr to PDF, the second set puts all of the equations on one line.

What can I do to fix this, please?

I also attached the entire file for ease of use.

Thank you for any help.

Sincerely,

Erin

[Yihui Xie]

http://lmgtfy.com/?q=latex+equation+break+into+two+lines#

$$
\begin{split}

E[X] = \lambda \cdot \dfrac{\Gamma(2)}{\lambda^2}
\left \lbrack \int_0^{\infty} \dfrac{\lambda^2}{\Gamma(2)}
x e^{-\lambda x} \; dx \right \rbrack, \\
E[X] = \lambda \cdot \dfrac{\Gamma(2)}{\lambda^2} \cdot 1, \\
E[X] = \dfrac{(2-1)!}{\lambda} = \dfrac{1}{\lambda}

\end{split}
$$

Regards,
Yihui
--
Yihui Xie <xiey...@gmail.com>
Web: http://yihui.name

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[Erin Hodgess]

This is so great!

Thank you very much!

(And my students thank you too...sort of!)

--

Erin Hodgess
Associate Professor
Department of Mathematical and Statistics
University of Houston - Downtown
mailto: erinm....@gmail.com