Hi guys,
I am using the code pasted below with the corresponding output:
syms X w t p
eq = X*cos(w*t – p)
eq =
X*cos(p – t*w)
The output is is reversed it should instead be X*cos(w*t – p). How would I change this?
MATLAB: Output of symoblic expression coming out incorrectly
equationsymbolic
Related Solutions
Try this:
syms A11 A12 A21 A22 B1 B2 A0 B0 A1 B1 C1 D1 w t Ps Pc km th(t) = A0*cos(w*t)+B0*sin(w*t)+B1*cos(2*w*t)+B1+C1*sin(2*w*t);thd=diff(th,t);thdd=diff(th,t,2);f=thdd-(A21-A22*(1+km*(sin(w*t)*Pc+cos(w*t)*Ps)))*thd-(A22*w*km*(cos(w*t)*Pc-sin(w*t)*Ps))*thd+B1*w*cos(w*t);fc = collect(f, [sin(w*t) sin(2*t*w) cos(w*t) cos(2*t*w)]) % Collected Terms
[fcc,T] = coeffs(f, [sin(w*t) sin(2*t*w) cos(w*t) cos(2*t*w)]) % Coefficients & Terms
produces:
fc(t) =(- A0*A22*Ps*km*w^2 - A0*A22*Pc*km*w)*sin(t*w)^2 + (- 2*A22*B1*Ps*km*w^2 - 2*A22*B1*Pc*km*w)*sin(t*w)*sin(2*t*w) + (A22*B0*Pc*km*w - A0*A22*Ps*km*w + A0*A22*Pc*km*w^2 + A22*B0*Ps*km*w^2)*sin(t*w)*cos(t*w) + (2*A22*C1*Ps*km*w^2 + 2*A22*C1*Pc*km*w)*sin(t*w)*cos(2*t*w) + (- B0*w^2 + A0*(A21 - A22)*w)*sin(t*w) + (2*A22*B1*Pc*km*w^2 - 2*A22*B1*Ps*km*w)*sin(2*t*w)*cos(t*w) + (- 4*C1*w^2 + 2*B1*(A21 - A22)*w)*sin(2*t*w) + (- A22*B0*Pc*km*w^2 + A22*B0*Ps*km*w)*cos(t*w)^2 + (- 2*A22*C1*Pc*km*w^2 + 2*A22*C1*Ps*km*w)*cos(t*w)*cos(2*t*w) + (B1*w - A0*w^2 - B0*w*(A21 - A22))*cos(t*w) + (- 4*B1*w^2 - 2*C1*(A21 - A22)*w)*cos(2*t*w) fcc(t) =[ - A0*A22*Ps*km*w^2 - A0*A22*Pc*km*w, - 2*A22*B1*Ps*km*w^2 - 2*A22*B1*Pc*km*w, A22*B0*Pc*km*w - A0*A22*Ps*km*w + A0*A22*Pc*km*w^2 + A22*B0*Ps*km*w^2, 2*A22*C1*Ps*km*w^2 + 2*A22*C1*Pc*km*w, - B0*w^2 + A0*(A21 - A22)*w, 2*A22*B1*Pc*km*w^2 - 2*A22*B1*Ps*km*w, - 4*C1*w^2 + 2*B1*(A21 - A22)*w, - A22*B0*Pc*km*w^2 + A22*B0*Ps*km*w, - 2*A22*C1*Pc*km*w^2 + 2*A22*C1*Ps*km*w, B1*w - A0*w^2 - B0*w*(A21 - A22), - 4*B1*w^2 - 2*C1*(A21 - A22)*w] T(t) =[ sin(t*w)^2, sin(t*w)*sin(2*t*w), cos(t*w)*sin(t*w), cos(2*t*w)*sin(t*w), sin(t*w), cos(t*w)*sin(2*t*w), sin(2*t*w), cos(t*w)^2, cos(t*w)*cos(2*t*w), cos(t*w), cos(2*t*w)]This enhancement has been incorporated in Release 2013a (R2013a). For previous product releases, read below for any possible workarounds:
In Symbolic Math Toolbox 5.4 (R2010a), SUBS can only be used to substitute a variable in an expression with another variable or expression. SUBS may not be used to substitute a sub-expression in an expression.
As a workaround, you can use SUBSEX, available in the MuPAD language, to substitute a sub-expression in an expression. You may call this function with the help of FEVAL as follows:
q = feval(symengine,'subsex',u,[char(w0) '=w0'])q =a*cos(t*w0 + 3) + b*sin(5*t*w0 + 3)You can also create an anonymous function to mimic SUBS:
subsx = @(u,w0,w0str) feval(symengine,'subsex',u,[char(w0) '=' w0str]);%then issuing the command:
p3 = subsx(u, w0, 'w0')You may read more about SUBSEX in the MuPAD help documentation at:
<http://www.mathworks.com/help/releases/R2013a/symbolic/mupad_ref/subsex.html>
Best Answer