MATLAB: Which curve fitting function do I need

Question

I want to fit the following function to measured data in order to estimate R:

D = atan2(sin(H),R*cos(H))

I have measured H & D

H will be in the range -1.1*pi/2 to 1.1*pi/2

I expect R to be approximately +2

To visualize, see:

figure
H = [-1.1*pi/2:0.1:1.1*pi/2]';
R = 2;
D = atan2(sin(H),R*cos(H));
plot(H,D)

I don't know which curve-fitting function to use. I have access to both the curve-fitting and optimization toolboxes. Any advice would be much appreciated.

Thanks

Answer 1

lsqcurvefit()  % optimization toolbox

or

lsqnonlin()