I have a matrix m with 9 rows and 4 columns and when I enter the command below I get an error message:

num := product((z-(m[s,1]+I*m[s,2])),s = 1..9);
Error, Matrix index out of range

However, there is no problem if I use brute force:

I played aorund a bit with the "Insert Table" command and it seems to create just an inert object that cannot be accessed or operated upon except directly by typing into its boxes. Is that true? Is it just for word processing?

Here is a simple sequcnce of commands that execute without a problem:
restart;
eq1 := 5+3*x=0:
eq2 := 2+7*x-3*y-5*x*y=0:
x:=solve(eq1,x):
y:=solve(eq2,y):
lprint('x'=x,'y'=y);


x = -5/3, y = 29/16

If I put the commands into a procedure there are problems:

I am using Maple 12.01 and I am using dsolve to solve a second order ODE;  example :

eq:=diff(y(t),t,t)+sin(t)*diff(y(t),t)+y(t)^2-5*y(t)=0;

ic:=a->[D(y)(0)=0,y(0)=a]; # initial conditions.
 

I want to investigate the  values of z(t, y, y') when g(t, y,y') = 0. Here z might be y''' or cos(t y') and g  might be y(t)-4.

What I would like to do is create an Array whose nth entry is of the form [ tn, z(tn,y(tn), y'(tn)]  where tn is the nth value of t at which the condition g(t, y,y') = 0 is satisfied.

Here is a recent session on Maple 12.1. The exact thing happens on Maple 11.5. I define a vector x , Maple acknowledges the fact but then if I ask if x is, in fact, that vector it says no. Any idea of what is going on? with(LinearAlgebra): > x := Vector(2, [1, 0]); Note Maple correctly prints transpose [1 0] on screen. [1] x := [ ] [0] if x=Vector(2, [1, 0]) then 7 else 3 end if; 3 is(x=Vector(2, [1, 0]));