Update on r codes

doc/src/How2ReadData/How2ReadData.do.txt

@@ -112,9 +112,11 @@ either Python or C++ as programming languages.
 To add more entropy, _cython_ can also be used when running your notebooks. It means that Python with the Jupyter/IPython notebook 
 setup allows you to integrate widely popular softwares and tools for scientific computing. With its versatility, 
 including symbolic operations, Python offers a unique computational environment. Your Jupyter/IPython notebook 
-can easily be converted into a nicely rendered _PDF_ file or a Latex file for further processing.
+can easily be converted into a nicely rendered _PDF_ file or a Latex file for further processing. For example, convert to latex as
+!bc pycod
+jupyter nbconvert filename.ipynb --to latex
+!ec
 
-This never ends.
 If you use the light mark-up language _doconce_ you can convert a standard ascii text file into various HTML 
 formats, ipython notebooks, latex files, pdf files etc. 
 
@@ -445,7 +447,7 @@ plt.show()
 !split
 ===== Linear Least squares in R  =====
 !bblock
-!bc pycod
+!bc r
 HudsonBay = read.csv("src/Hudson_Bay.csv",header=T)
 fix(HudsonBay)
 dim(HudsonBay)
@@ -471,7 +473,7 @@ predict(linearMod,data.frame(Year=c(1910,1914,1920)),interval="confidence")
 !split
 ===== Non-Linear Least squares in R  =====
 !bblock
-!bc pycod
+!bc r
 set.seed(1485)
 len = 24
 x = runif(len)