// This function "peak_detect.sci" detect the peaks of a signal :
// -------------------------------------------------------------
// For an input row vector "signal" , the function return
// the position of the peaks of the signal.
//
// The ouput "peaks" is a row vector (size = number of peaks),
// "peaks" =[] if no peak is found.
//
// Optional argument "threshold" eliminates the peaks under
// the threshold value (noise floor).
//
// Clipped peaks (more than 2 samples of the signal at the same value)
// are not detected.
