.de BR
.in 0
.in +8n
.ti -3n
..

.Th DECIMATE
.S2 SUMMARY:
Decimate trace by an integer

DECimate  [n]

.S2 INPUT:
[n]      : decimation factor - an integer

.S2 DESCRIPTION:
This routine decimates a trace by outputting the first and then every n points.
The resultant time series changes length.
.sp
NOTE THE DECIMATION FACTOR IS NEVER REMEMBERED - THE DEFAULT IS ALWAYS 1
.S2 "SAC COMPATIBILITY:"
Sac limits the decimation interval to 2 <= n <= 7. This is because Sac permits an anti-aliasing filter option which meant that those filter coefficients must be built into the program.
.sp
In the GSAC implementation, I suggest a zero phase low pass filter
at a frequency 0.5 the Nyquist frequency, or 0.25/DELTA, perhaps a
.BR
lp c corner_frequency n 4 p 2

.S2 EXAMPLES:
dec  2
.S2 "HEADER VALUES SET:"
NPTS, DELTA, B, E, DEPMIN, DEPMAX, DEPMEN

.S2 "DEFAULT":
decimate 1

