Fminsearch not resloving the optimization problem

I am writing a matlab program for optimization of two variables to minimize my Standard Deviation. My two variables 'T' & 'D' have been put in a matrix. The function relating these variables is S=T.*cos(D*pi/180)+0.8 The standard deviation is between tge calculated 'S' as per the above formula and a measured value 'P'. Now i need to optimise T and D to have a minimum standard deviation. I tried the fminsearch function but not getting it