In this case, eqns is not a symbolic expression, but a logical value that will be true if
x1 * str2num(app.Entry11.Value) == b1
and false otherwise.
When you call the solve function, the parameter passed to the function is either a 0 or a 1, not a symbolic expression. To make it work you should counsider writing this code:
if app.SysOrder >= 1
b1 = str2num(app.Source1.Value);
eqns = x1 * str2num(app.Entry11.Value) - b1;
end
S = solve(eqns, x1);
app.Solution1.Value = [num2str(S.x1)];
Instead of considering the equation as f(x) = b, you consider it as f(x) - b = 0, because the only form that the solve function can work on is f(x) = 0, and then solve for x.
Please respond on this post to let me know if this solves your problem!
