Hi, I understand you are getting issues in removing all the coefficients from a given equation. You can do this by doing following adjustments to your code-
- Create an array of coefficients need to be replaced using syms function.
- Through an iteration substitute all the coefficients using subs function.
- Collect required expression through collect function.
Here is a sample code for it.
clc;
clear all;
% coeffs a_k, b_k
syms a0
syms a [1,2]
syms b [1,2]
coeffs = [a0 ,a1, a2, b1, b2];
% sin cos parts of function
trigs = [cos([1 2]*sym('tau')), sin([1 2]*sym('tau'))];
% combine
initFC = symfun(sum([1 trigs] .* coeffs), [coeffs sym('tau')]);
% Equation
F([coeffs sym('tau')]) = initFC.^2 == 0;
F = expand(F);
F = combine(F, 'sincos');
syms Z [8,1]
syms tau
%Coefficients to be replaced
coff_eqn=[cos([1 2 3 4]*tau), sin([1 2 3 4]*tau)];
for i=1:length(coff_eqn)
F = subs(F, coff_eqn(i), Z(i));
end
expr=collect(F,[Z(1:7)]);
display(expr);
espr=children(expr); % Find LHS of the expression
final=children(espr{1});
for i=1:length(coff_eqn)
Out(i)=final{i};
Out(i)=subs(Out(i), Z(i), 1);
end
display(Out);
The output is
