MATA Error "Nothing found where while expected"

[Lars Pete]

I am studying from the STATA guide.
I typed MATA and then copied and entered the following command as shown in the entry for STATA:

: real matrix id(real scalar n)
{
real scalar i
real matrix res
res = J(n, n, 0)
for (i=1; i<=n; i++) {
res[i,i] = 1
}
return(res)
}
:
: I3 = id(3)
: I3

Which gives the error: nothing found where 'while' expected
r(3000);

Any help is much appreciated.

[William Lisowski]

I am unable to duplicate your experience. I include mata clear as the first command to be sure nothing is left from my previous testing. This was copied and pasted as one into Stata's Command window; it works equally well run from the Do-file Editor window.

. clear all

. mata
------------------------------------------------- mata (type end to exit) ----------------------
: mata clear

: real matrix id(real scalar n)
> {
> real scalar i
> real matrix res
> res = J(n, n, 0)
> for (i=1; i<=n; i++) {
> res[i,i] = 1
> }
> return(res)
> }

: I3 = id(3)

: I3
[symmetric]
       1   2   3
    +-------------+
  1 |  1          |
  2 |  0   1      |
  3 |  0   0   1  |
    +-------------+

: end
------------------------------------------------------------------------------------------------

.

[Lars Pete]

William, Thank you very much! This worked like a charm.
Best,
Lars.