sin cosin regression fit and finding coefficients of interpolated equation

Dear matlab users,

I have a question, was wondering if you could help me out to solve it in MATLAB. There are sets of data points t,y ,which i want to interpolate my data(or regression-least square) with a sine,cosine interpolation and obtain the amplitudes of sine ,cosine equation in this format (y=a*cos(wt)+b*sin(wt)), (a and b)< >temp, in a y direction and t is defined in x direction and w is frequency and has a constant value of 3.17e-08.

time          temp
0             5
2592000       -5
6480000       -10
14256000      -18
27216000      -8
42768000      0
60048000      3
82512000      15
108432000     13
139968000     3

Its really appreciated

Regards,