110179     Fast Fourier Transform Routine  Version: February 1975
 
Submitted by: Digital Equipment Corporation
 
Source Language: MACRO-11  Keywords: Scientific Applications
 
Abstract: FFTR is a PDP-11 assembly language subroutine which
performs a 16-bit precision forward or inverse Fast
Fourier Transform of N real-valued data points, where N
is a power of 2 in the range 16 less than or equal to
N less than or equal to 2048. A sample size of
2048 points if transformed in 1.21 seconds on a PDP-11/20
with EAE. Accuracy is preserved by scaling only when
overflow occurs. FFTR requires about 1400 words of memory,
exclusive of the user supplied N+2 word buffer. It can
be called from FORTRAN under DOS or RSX-11D/M or linked
with an assembly language program. Versions are available
for all PDP-11's and no hardware arithmetic unit is required.
However, use of a hardware arithmetic unit greatly
improves the speed of FFTR and special versions of the
routine are available for machines which are equipped
with EAE or EIS.
 
Documentation available in hardcopy only.
 
Media (Service Charge Code): Write-Up (AA), One RX01 Diskette (KA)
Format: RT-11, 600' Magnetic Tape (MA)  Format: DOS-11