int im_mean_std_int_buffer(buf, size, mean, std)
int *buf; int size; double *mean, *std;
int im_mean_std_double_buffer(buf, size, mean, std)
double *buf; int size; double *mean, *std;
im_mean_std_int_buffer() and im_mean_std_double_buffer()
calculate the mean and the standard deviation (std) of data held by the
integer or double buffer buf. The buffer has size elements. The results are
returned to the locations pointed by mean and std.
It is the responsibility of the calling function to ensure that there is
enough data in the buffer.
Both functions returns 0 on success and -1 on error.