optimisation and curve fitting possibly by lsqcurvefit

Hello,

Does anybody know how I could solve this equation using lsqcurvefit or any other way in Matlab to optimise c(1) to c(5) and to minimise the error? The values of xdata, ydata, a, and b are known. I think 'y' should be on the other side of the equal sign in order to be able to use lsqcurvefit which makes it difficult to use lsqcuvefit in this problem as it is impossible to transfer 'y' to the other side of the equal sign!

Error=sum(((ycos(c1)-xsin(c1))-((a^c2+ b^c3)^c4)*b+a*c(5))^2+((ysin(c1)+xcos(c1))-((a^c2+ b^c3)^c4)*b+a*c(5))^2)

Many thanks,

Kourosh