mags
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## mags

mags — Obtains the magnitudes of a complex-number array

## Description

This opcode returns the magnitudes of a complex-number array (in rfft format), as a real-valued array with half the size of its input plus one. The magnitude for the Nyquist frequency are kept in the last position of the array.

## Syntax

    kout[] mags kin[]

## Performance

kout[] -- output array containing the magnitudes (size = input_size/2 + 1). It will be created if it does not exist.

kin[] -- input array containing the complex-valued real-imaginary input.

## Examples

Here is an example of the mags opcode. It uses the file mags.csd.

Example 556. Example of the mags opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    -d -o dac
    </CsOptions>
    <CsInstruments>
    /* ksmps needs to be an integer div of
       hopsize */
    ksmps = 64
    0dbfs=1
    nchnls=2

    opcode PVA,k[]k[]k,aii
     asig,isize,ihop xin
     iolaps init isize/ihop
     kcnt init 0
     krow init 1
     kIn[] init isize
     kOlph[] init isize/2 + 1
     ifac = (sr/(ihop*2*$M_PI))
     iscal = (2*$M_PI*ihop/isize)
     kfl = 0
     kIn shiftin asig
     if kcnt == ihop then
       kWin[] window kIn,krow*ihop
       kSpec[] rfft kWin
       kMags[] mags kSpec
       kPha[] phs kSpec
       kDelta[] = kPha - kOlph
       kOlph = kPha
       kk = 0
       kDelta unwrap kDelta
       while kk < isize/2 do
        kPha[kk] = (kDelta[kk] + kk*iscal)*ifac
        kk += 1
       od
       krow = (krow+1)%iolaps
       kcnt = 0
       kfl = 1
     endif
     xout kMags,kPha,kfl
     kcnt += ksmps
    endop

    opcode PVS,a,k[]k[]kii
     kMags[],kFr[],kfl,isize,ihop xin
     iolaps init isize/ihop
     ifac = ihop*2*$M_PI/sr;
     iscal = sr/isize
     krow init 0
     kOla[] init isize
     kOut[][] init iolaps,isize
     kPhs[] init isize/2+1
     if kfl == 1 then
      kk = 0
      while kk < isize/2 do
        kFr[kk] = (kFr[kk] - kk*iscal)*ifac
        kk += 1
      od
      kPhs = kFr + kPhs
      kSpec[] pol2rect kMags,kPhs
      kRow[] rifft kSpec
      kWin[] window kRow, krow*ihop
      kOut setrow kWin, krow
      kOla = 0
      kk = 0
      until kk == iolaps do
       kRow getrow kOut, kk
       kOla = kOla + kRow
       kk += 1
      od
      krow = (krow+1)%iolaps
     endif
     xout shiftout(kOla)/iolaps
    endop

    instr 1

     ihopsize = 256  ; hopsize
     ifftsize = 2048 ; FFT size
     kFreqsOut[] init ifftsize/2+1 ; synthesis freqs
     kMagsOut[] init ifftsize/2+1 ; synthesis mags

     a1 diskin2 "fox.wav",1,0,1

     kMags[],kFreqs[],kflg PVA a1,ifftsize,ihopsize

     if kflg == 1 then
     ki = 0
       kMagsOut = 0
      kFreqsOut = 0
      iscal = 1.5
     until ki == ifftsize/2 do
       if ki*iscal < ifftsize/2 then
         kFreqsOut[ki*iscal] = kFreqs[ki]*iscal
         kMagsOut[ki*iscal] = kMags[ki]
       endif
        ki += 1
      od
     endif

     a2 PVS kMagsOut,kFreqsOut,kflg,ifftsize,ihopsize

     a1 delay a1, (ifftsize+ihopsize)/sr
        outs a1, a2
    endin

    </CsInstruments>
    <CsScore>
    i1 0 10
    </CsScore>
    </CsoundSynthesizer>

## See Also

Vectorial opcodes, array opcodes

## Credits

Author: Victor Lazzarini
NUI Maynooth
2014

New in version 6.04

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