Simple symmetrical wave RMS DEMO using awk. Post: 303002987

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Operating Systems OS X (Apple) Simple symmetrical wave RMS DEMO using awk. Post 303002987 by wisecracker on Wednesday 6th of September 2017 09:04:12 AM

09-06-2017

Registered User

Hi JM...
(Thanks for the reply.)
Apologies for any typos, and hope it is lucid enough.

Quote:

Originally Posted by jim mcnamara

It looks to me like you have a granularity problem. Four dots as a sample can fit a lot of functions, with intermediate datapoints from increased sampling rates you could then use fft to get good sine waves, for example.

You can code fft.c then call it using the system() function in awk. I think your awk supports that call.

A google for 'fft.c' got me 10 first page hits that looked respectably good. There are sites with an array of algorithmic variants to meet differing needs.

fft is gold standard for fitting data sampling output.

Apologies for the delay, I have not been around for a while. My triangle wave is more or less hypothetical as sampling a real time random triangle wave that......
1) starts at the 0 point,
2) is initially positive going,
3) has 4 samples, or any number of the same 4 samples,
......is close to impossible.
But a file CAN be so easily be created as shown in the single cycle version in the code.
Although I was aware of the errors that creep in when creating the RMS values I was NOT aware of this one off bizarre situation, (and could find nothing on the WWW about it), so after creating the simple code I made a point of there being a reference to this anomaly.

As the RMS value(s) are near the exact value(s) for that of a sinewave hence my point.

In the days of Debian 6 and PCLinuxOS 2009, (my two main OSes in those days), when '/dev/dsp' was available, recreating the waveforms through '/dev/dsp' would result in a triangle wave as the sound system interpolation was Linear, this was also true for some Windows machines of bygone days. I am not sure what interpolations are used in current OSes and sound systems but it sure looks trigonometric to me, so I would guess that a sinewave would be recreated as a result.

I am happy with the idea of the RMS code at this point but looking more towards True RMS but would probably need to rethink my approach.

But to re-iterate for others, be aware of this anomaly.

LBNL, for any FFT work needed, I would do it through Python and SciPy as the heavy lifting is done already, see previous uploads of AudioScope.sh for the AF Spectrum display...

Bazza...

Last edited by wisecracker; 09-06-2017 at 12:18 PM.. Reason: Modify for error...

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LEARN ABOUT OPENDARWIN

sfind

sfind(1)							    ShapeTools								  sfind(1)

NAME

       sfind - shapeTools RMS recursively descend a system hierarchy

SYNOPSIS

       sfind [-subs | -comp] directory [command]

DESCRIPTION

       Sfind  recursively descends the system hierarchy of a software system managed by the shapeTools Release Management System (shapeTools RMS).
       Sfind starts it's search from directory downwards. According to the shapeTools RMS conventions, directory must contain  a  Shapefile  which
       lists the subsystems in the variable SUBSYSTEMS and the subsystem components in the variable COMPONENTS. Each subsystem is visited.

       If  no  command is specified, sfind echoes the pathnames of the subsystems it finds, or, if the option -comp is given, the pathnames of the
       components of each subsystem.

       When a command is given, it is executed in the directory of each subsystem.  The string ``{}'' in command is replaced by  the  pathname	of
       the subsystem or component.

OPTIONS

       -subs  command is invoked for each subsystem.  This is the default.  ``{}'' in command is replaced by the pathname of the subsystem.

       -comp  command is invoked for each component.  ``{}'' in command is replaced by the pathname of the component.

EXAMPLES

       List all system components:

	      sfind -comp ~/development

       Show the pathnames of all versionfiles:

	      sfind ~/development echo -n {}/ ; shape -echo VERSIONFILE

       Echo identification of the last release of each subsystem:

	      sfind ~/development vl -last -format 
		  '$__lastrelease$\n'	   
		  `shape -echo VERSIONFILE`

       Necessary quoting to echo a pair of curly braces:

	      sfind ~/development echo two \{\} braces

SEE ALSO

       find(1), sh(1), shape(1), shape_RMS(1), shape_tmpl(7)

CAVEATS

       Quoting of shell meta characters can be tough.

BUGS

       The program is slow because shape(1) is called at least once for each subsystem.

       When sfind is interrupted, usually shape(1) displays the message ``shape - interrupted'', which may be confusing.

AUTHOR

       Andreas.Lampen@cs.tu-berlin.de

shape_RMS-1.15						     Fri Jun 25 17:01:50 1993							  sfind(1)