MaplePrimes - answers and comments on Question, Function subs gives rise to lots of unexpected (0) and (1)

Use eval instead

Preben Alsholm — Thu, 07 Mar 2013 18:45:24 Z

You can use eval instead. Compare:

u:=sin(x)+cos(y);
subs({x=Pi/4,y=Pi/2},u);
%;
# with
eval(u,{x=Pi/4,y=Pi/2});

# and see

?subs
where it says:

" Simple applications of replacing a symbol by a value in a formula should normally be done with the eval command."

PlpPlp — Thu, 07 Mar 2013 19:19:31 Z

Here it is:

Preben Alsholm — Thu, 07 Mar 2013 20:04:30 Z

Try

indets(ratio,function);

and you will see expressions like

B[1](m[10]^2+m[20]^2)

These are of type function in Maple, same as f(x) or f(2).
The expression should have been
B[1]*(m[10]^2+m[20]^2)

You may try to repair the damage the easy way:

newratio:=evalindets(ratio,function,x->op(0,x)*op(1,x)):
eval(newratio, [m[10] = 0, m[20] = 0, m[30] = 1]);

PlpPlp — Thu, 07 Mar 2013 18:55:43 Z

I should have mentionned that in my first post. I tried eval as well and I got the same results, surprisingly...

Carl Love — Thu, 07 Mar 2013 19:06:22 Z

@PlpPlp Upload the long expression.

PlpPlp — Thu, 07 Mar 2013 23:28:05 Z

That worked perfectly, thanks a lot! I guess the Maple GUI would need some refinements for novices like me!