MATLAB: Need help in this

inputs must be floatsmatrixodeSymbolic Math Toolbox

Hello everybody
i just have this code:
syms w1 w2 w3 w4 v1 v2 x1 x2 yd
n1=w1*x1+w2*x2;
o1=1/(1+exp(-n1));
o1_der=o1*(1-o1);
%%



n2=w3*x1+w4*x2;
o2=1/(1+exp(-n2));
o2_der=o2*(1-o2);
%%
n3=v1*o1+v2*o2;
o3=(1/(1+exp(-n3)));
o3_der=o3*(1-o3);
e1=(o3-yd);
%%
A1=((o1^2+o2^2)*o3_der^2 +(x1^2+x2^2)*(v1^2)*o1_der^2*o3_der^2+(x1^2+x2^2)*(v2^2)*(o2_der^2)*o3_der^2);
%%
aa=e1*A1;
aw1=diff(aa,w1);
I need to take (aw1) which is derived (aa) respect to (w1) then use it in b.m file for example.. (aw1 is symbolic i mean all values inside are varibals).
The error below occure when i save aw1 as a data and load it in another file and run
(Inputs must be floats, namely single or double.
Error in ode15s (line 150)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
Error in simple (line 44)
[T1,cox]=ode15s(@(t,y1) Costatesimple(t,y1,u,x1,x2,yd,x1t,e1,w1,w2,w3,w4,v1,v2),tspan2,[0 0 0 0 0 0 0],options);
any help please?
however, it works when i copy all values insied aw1 and paste it in b.m file..
due to the value of aw1 is too long so, i need way to move it to another file without copy and paste
i would you to help in this issue please.

Best Answer

When saving aw1 in a.m you need to save all other symbolic variables too
save('filename.mat', 'aw1', 'w1', 'w2', 'w3', 'w4', 'v1', 'v2', 'x1', 'x2', 'yd' );
and then load the file in b.m 
load('filename.mat');
Alternatively, you can also try to just save aw1
save('filename.mat', 'aw1')
and then in b.m write
load('filename.mat');
syms w1 w2 w3 w4 v1 v2 x1 x2 yd
For a bit detailed discussion on this topic, refer to Walter's answer and my comments here: https://www.mathworks.com/matlabcentral/answers/513625-how-to-save-a-symbolic-equation-in-a-txt-file#answer_422592
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