band - generates band of frequency components with spacing and amplitude control

band output[b] amp[bvpn] afac[bvpn] inca[bvpn] incb[bvpn] ifac[bvpn] 
 table[fvpn] sum[dpv] ;

Outputs several waveforms at once at frequencies in band corresponding
to inca through incb.  If ifac is positive, it is ADDED repeatedly to
inca to get each new frequency; if it is negative, its absolute value
is MULTIPLIED repeatedly to get new frequencies (-2 gives all octaves,
for example).  The first frequency component has an amplitude specified
by amp; afac is MULTIPLIED by amp for the second component, MULTIPLIED
again for the amplitude of the third, etc.  The output has peak
amplitude equal to the sum of the amplitudes of the components
generated, which depends on the size of the band, their spacing, and
afac. If afac = 1.0, then the output signal has amplitude N*amp, where
N if the number of components generated.
