## Exercise: Fast Fourier Transform

You are provided with a routine to calculate
a Fast Fourier
Transform (FFT) which is written in C. The function is called
**fft** and takes as its arguments the double complex array of data
and the integer number of data points.

Your task is to write a program to read a number of data files as specified on the command line and using the supplied C routine, produce output files for each consisting of the resultant transforms.

The provided data sets are:

The first line in each data file is the total number of data points (as an integer). Each subsequent line is a single data point containing the real and imaginary components. You are encouraged to use the same format for your output files.

The FFT alogrithm in C is taken from the Rosetta Stone version. You will need to specify the C99 standard when compiling this routine.

Solution: Fortran