#
# Fourier Synthesis
#
sub fourier {
    my ($s1,@spectrum) = @_;
    my $coef;
 
    foreach $coef (@spectrum) {
        my @fpa = split /_/, $coef;      # get frequency,phase and amplitude
        &osc::sinus($s1,$fpa[0],$fpa[1],$fpa[2],1);
    }
}

##</code><code>##

#
# set the maximum amplitude to 1/-1
#
sub normalize {
    my $s1  = shift;
    my $max = &max($s1);
 
    &scale($s1,1/$max) if $max;
}
 
#
# reduce/expand the frequency of a given sample
#
sub redex {
    my ($s1,$new_freq) = @_;
    my $old_freq       = $$s1[$SMP_FREQ];
    my $cells          = $$s1[$SMP_CELLS];
    my $redex          = $new_freq / $old_freq;
 
    return if($redex == 1);                 # Nothing to be done
 
    my $newcells = $cells * $redex;
    my $a;
 
    if($redex > 1) {                        # Expand the original sample
 
    } elsif($redex < 1) {                   # Reduce the original sample
        for($a = 0; $a < $newcells; $a++) {
            $$s1[$a + $SMP_DATA] = $$s1[$a/$redex + $SMP_DATA];
        }
        $$#s1 = $newcells + $SMP_DATA;
    }
    $$s1[$SMP_CELLS] = $newcells;           # update the amount of cells in sample
}