Struggling with CAS programming

[Didier Lachieze]

Two things :

1. I've found you need to declare your local variables before assigning them
2. the line a(lpv,lpv+1) = 1; should be replaced by a[lpv,lpv+1]:=1;
   

Code:

#cas
tf2ss(num,den):=
BEGIN
// declare vars and allocate matrices
local ordem,a,b,c,d;
ordem := size(den)-1;
a:= identity(ordem)*0;
b:= identity(ordem)*0;
c:= revlist(num);
d:=0;
// fill A is in the form [0 1 0; 0 0 1; -p/m -o/m -n/m], where n m o p are from den
a:= replace(a,{ordem,1},-revlist(den[2..(ordem+1)])/den(1));
FOR lpv FROM 1 TO ordem-1 DO
a[lpv,lpv+1]:=1;
end;
// fill b 
b:= delrows(b,2..ordem);
b:= replace(b,{1,ordem},[1]);
b:= tranpose(b);

return a;
//return b;
//return c;
//return d;
END;
#end