# Question: Declaring an identity of an unknown function in Maple...

February 12 2013 by
false
Maple

0

Hi,

I was wondering, suppose I have an ordinary differential equation, y''(x)  + y(x) - y(x)^3, and that the RHS is equal to zero (Duffing type equation).. Is there any way to declare this as in Maple, such as,

y''(x):=y(x)^3-y(x);

so that any time Maple sees y''(x) + y(x)-y(x)^3 in an expression, it will replace it with zero? I have tried the above, but it receive an error which says, "error, illegal use of an object as a name."