need solution with symbolic

Dear all

why the first code is working otherwise in second code when I just change a bit it won't work ?

The first code

syms z2 
Z2(z2) = piecewise(0<=z2, z2, 0>z2, 0.2*(exp(z2)-1));
Z2([10])

The second code

syms  w12 a1 b12 z2 
z2 = w12*a1 + b12;
Z2(z2)=piecewise(0<=z2, z2, 0>z2, 0.2*(exp(z2)-1));
Z2([10])

Any suggestion please?

Answer 1

[Ameer Hamza]

Here:

Z2(z2)=piecewise(0<=z2, z2, 0>z2, 0.2*(exp(z2)-1));
  %^

z2 is not an independent symbolic variable. It is a symbolic expression. You should use the base variables to make symbolic functions. For example

syms  w12 a1 b12 z2 
z2 = w12*a1 + b12;
Z2(w12,a1,b12)=piecewise(0<=z2, z2, 0>z2, 0.2*(exp(z2)-1));
Z2(10, 1, 2)

[Ali Najem]

it worked thanks alot sir

[Ameer Hamza]

I am glad to be of help!