Well guys, it took a while because of the serious limitations of ARexx for a stock AMIGA A1200 but here is a working FFT for it. ARexx has no ARRAY facility but there is a workaround. ;o)
Boy oh boy, ARexx's arithmetic is so convoluted and floating point precision is not the best.
This was a challenge. I could have generated SIN, COS and SQRT in pure ARexx but decided to use an external ARexx math(s) library instead...
It would be just as easy to create SIN, COS and SQRT in ksh too eliminating awk entirely but awk just made it easier...
Just for the record the AMIGA shell/terminal has a large subset of xterm's escape codes.
An exercise in futility? Maybe but serious fun nevertheless...
This is through FS-UAE AMIGA emulation and my real A1200 setup for easy transfer from this Macbook Pro.
ARexx code:
Code:
/* Simple_FFT_DEMO.rexx */
/* This ARexx version needs this dependency: */
/* http://aminet.net/package/util/rexx/RexxMathLib */
CALL ADDLIB('rexxmathlib.library',0,-30,0)
NUMERIC DIGITS 14
SAY ""
SAY "An experimental method to do an FFT in ARexx using the standard test values."
SAY "It requires rexxmathlib.library for the SIN and COS."
SAY "$VER Simple_FFT_DEMO.rexx_(C)06-09-2018_B.Walker_issued_under_GPL2."
SAY ""
/* Create standard test _ARRAYS_ REAL and IMAGINARY. */
/* These MUST be powers of 2 and greater than 2 in size. */
/* Real values, '1.0 1.0 1.0 1.0 0.0 0.0 0.0 0.0' */
/* Imag values, '0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0' */
/* Not really ARRAYS but good enough for this DEMO! */
DO N=0 TO 3 BY 1
REAL_ARRAY.N=1.0
END
DO N=4 TO 7 BY 1
REAL_ARRAY.N=0.0
END
DO N=0 TO 7 BY 1
IMAG_ARRAY.N=0.0
END
/* Display them. */
SAY "Input, REAL: IMAG:"
DO N=0 TO 7 BY 1
SAY " "||REAL_ARRAY.N||" "||IMAG_ARRAY.N
END
/* Only constant required, 14 decimal places. */
PI=3.14159265358979
/* N should be 8 by default in this DEMO. */
/* SAY "Number of elements = "||N||"..." */
N=N-1
CALL FFT
SAY ""
DO N=0 TO 7 BY 1
SAY "REAL: "||+OUT_REAL.N||", IMAG: "||+OUT_IMAG.N
END
SAY ""
SAY "Final FFT values to 5 decimal places:"
STR=""
DO N=0 TO 7 BY 1
CALL ABS_COMPLEX
NUMERIC DIGITS 14
IF +ABS <= 0.000000000001
THEN
ABS=0
ENDIF
NUMERIC DIGITS 6
STR=STR||+ABS||" "
END
SAY STR
SAY ""
EXIT
/* Create the subroutines required. */
/* FFT subroutine. */
FFT:
DO K=0 TO N BY 1
SUMREAL=0.0
SUMIMAG=0.0
DO T=0 TO N BY 1
ANGLE=(2.0*PI*T*K)/(N+1)
SUMREAL=SUMREAL+(REAL_ARRAY.T*COS(ANGLE))+(IMAG_ARRAY.T*SIN(ANGLE))
SUMIMAG=SUMIMAG-(REAL_ARRAY.T*SIN(ANGLE))+(IMAG_ARRAY.T*COS(ANGLE))
END
OUT_REAL.K=SUMREAL
OUT_IMAG.K=SUMIMAG
END
RETURN
/* FFT subroutine end. */
/* Absolute value of complex number subroutine. */
ABS_COMPLEX:
ABS=SQRT( (OUT_REAL.N**2)+(OUT_IMAG.N**2) )
RETURN
/* Absolute value of complex number subroutine end. */
Hello All,
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Discussion started by: wisecracker
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LEARN ABOUT OPENSOLARIS
sleep
sleep(1) User Commands sleep(1)NAME
sleep - suspend execution for an interval
SYNOPSIS
/usr/bin/sleep
/usr/bin/sleep time
ksh93
sleep time
DESCRIPTION
/usr/bin/sleep
sleep suspends execution for at least the integral number of seconds specified by time.
ksh93
sleep suspends execution for at least the time in seconds specified by time or until a SIGALRM signal is received.
OPERANDS
/usr/bin/sleep
The following operands are supported for /usr/bin/sleep:
time time in seconds can be specified as a non-negative decimal integer number.
ksh93
The following operands are supported:
time Specify time in seconds as a floating point number. The actual granularity depends on the underlying system, normally around 1 mil-
lisecond.
EXAMPLES
Example 1 Suspending Command Execution
The following example executes a command after a certain amount of time:
example% (sleep 105; command)&
Example 2 Executing a Command Every So Often
The following example executes a command every so often:
example% while true
do
command
sleep 37
done
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of sleep: LANG, LC_ALL, LC_CTYPE, LC_MES-
SAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0 The execution was successfully suspended for at least time seconds, or a SIGALRM signal was received (see NOTES).
>0 An error has occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
/usr/bin/sleep
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
|Standard |See standards(5). |
+-----------------------------+-----------------------------+
ksh93
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
|Interface Stability |Uncommitted |
+-----------------------------+-----------------------------+
SEE ALSO ksh93(1), wait(1), alarm(2), sleep(3C), wait(3UCB), attributes(5), environ(5), standards(5)NOTES
If the sleep utility receives a SIGALRM signal, one of the following actions is taken:
o Terminate normally with a zero exit status.
o Effectively ignore the signal.
The sleep utility takes the standard action for all other signals.
SunOS 5.11 20 Nov 2007 sleep(1)