Data Frequency Analysis and Calculations C Function

Need a function in C that will analyze an array of data and calculate what the period of the wave is, the amplitude of the wave is, the starting point and the ending point. The function can use a global defined array of data and can look like: for example: double data[2000] int get_frequency_data(double *dperiod, double *damplitude,int *istart,int *iend); where: dperiod returns the period of the wave seen on the data. Like the number of points between each peak or each valley. damplitude returns the average amplitude seen on the wave istart returns the point where this period and amplitude starts iend returns the point where this period and amplitude ends. We expect the data to contain only one type of wave. we don't expect the data to contain more than one wavelength. The function must be in plain C language. Enclosed are examples of real data we need to analyze.