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