[R] question involving loops from intro level R programming class

Richard.Cotton at hsl.gov.uk Richard.Cotton at hsl.gov.uk
Fri Nov 28 11:02:36 CET 2008

> a. Write a R function zerdiag.v1(m) using loop to output a square matrix
> whose diagonal elements are zero and the other elements are filled in by
> consecutive integers from 1 to m row-wise.
> For example,
> zerdiag.v1(6) =  [0, 1, 2]
>                           [3, 0, 4]
>                           [5, 6, 0]
> This function should have error checking ability. If the input m cannot 
> a square matrix, then the function will return an error message: "Input
> number is incorrect."
> b. Write a R function zerdiag.v2(m) to produce the same output as in 
> (a) without using a loop.
> c. Test your functions in part (a) and (b) using m=12 and m=14 
> I'd appreciate any help with this problem... I've spent a lot of time
> staring at it, and I'm still not sure where to start. Thanks!

As the posting guide (http://www.r-project.org/posting-guide.html) says
"Basic statistics and classroom homework: R-help is not intended for 
these. "

Also, I find it a little bit cheeky that you''ve asked for help on 3 parts 
of your homework, and haven't provided any evidence that you've even 
attempted the problem yourself.  (If you've been staring at the problem 
for hours, you must have written something.)  Read the help pages ?matrix 
and ?"for" and take a look in the Intro to R manual.


Mathematical Sciences Unit


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