On the left side of the = (assignment) operator, there should be a variable or a writeable predefined symbol. This implies that you cannot assign anything to a function, like real(z) or imag(z). Example:
real(z) = 3 * |z|
should be changed to
z = 3 * |z| + flip(imag(z))
Or better yet, assign the result to a float variable (instead of to a complex one):
float x = 3 * |z|
This error is also often generated when the = and == operators are confused. Example:
if 3 * x = y
Correct this to:
if 3 * x == y
See Also
Errors