Store as array not variable

I have the following function:

function f = function42(params2,T0,theta_f)
% f = x^2 %f and x are dummy variables
global a b
nu = params2(1);
phi = params2(2);
wf2 = params2(3);
c1 = b^2*(((exp(a*2*pi)-cosh(a*b*T0))/sinh(a*b*T0))^2-1);
Fitted_Curve = c1*exp(-2*a*theta_f)+nu*((1+0.5*(4*a^2+1))*cos(theta_f+phi)-2*a*sin(theta_f+phi))+b^2-wf2
f = sum(abs(Fitted_Curve));

T0 and theta_f are 1x9 vectors Fitted_Curve comes out in the workspace as a 1x9 vecot also, however c1 does not, it comes out as a variable and therefore i dont think it is using the corresponding T0 with theta_f for each calculation. My question is how do i get c1 to be a vector so that the corresponding c1 is used with the corresponding theta_f in the equation Fitted_curve.

Side note.

anyone know if i am doing the least squares method correctly here in this function.

Answer 1

[Matt Tearle]

The classic trap!

c1 = b^2*(((exp(a*2*pi)-cosh(a*b*T0))/sinh(a*b*T0))^2-1);

The divide there will be interpreted as a matrix divide (ie solving a matrix equation). Sounds like you were wanting elementwise calculation, so change the / into a ./ Similarly, you will also need to change c1*exp(-2*a*theta_f) on the next line to c1.*exp(-2*a*theta_f)

As to the side note: try f = norm(Fitted_Curve) or f = Fitted_Curve*(Fitted_Curve') if you want least squares.

Also, finally: don't use global! Pass a and b in as parameters. If necessary, use anonymous function handles to "wrap" function42.

[Alex]

Cheers Matt for your help. I have made those changes however it now says that Matrix must be square in the c1 line. the only thing in there is the T0 which is a 9x1 vector

T0 = [1.449 1.442 1.544 1.512 1.511 1.515 1.623 1.637 1.519];

[Matt Tearle]

Oops, missed the ^2 Guess what, that should be a .^2. Any multiplicative operator (/ \ * ^) will be interpreted in a matrix sense. The elementwise equivalent is made by preceding with a dot (./ .\ .* .^)