I guess, this line is failing:
Jsx*der(wx) = (Fflz + Frlz)*w/2 - (Ffrz + Frrz)*w/2 + (Ffyv + Fry)*h;
Yes, of course. In Matlab the = is the operator for assigning a value to a variable. The shown line is a methematical formula, but not a valid Matlab instruction. You need a variable on the left hand side of the =.
This will not work also:
(Fflz - (Fsfl + Fdfl))*w/2 - (Ffrz - (Fsfr + Fdfr))*w/2 + Ffy*hRCf = 0;
What is the meaning of tis line:
It is not clear, what you try to achieve. The posted text is no Matlab code.