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Groups > comp.lang.python > #45576

Re: Harmonic distortion of a input signal

Date 2013-05-19 21:11 -0400
From Dave Angel <davea@davea.name>
Subject Re: Harmonic distortion of a input signal
References <eb271b5d-ee83-4f0e-b8ea-5b129c7cb771@googlegroups.com> <bdb22ed6-69a0-48f4-b975-e9af31b72f39@googlegroups.com>
Newsgroups comp.lang.python
Message-ID <mailman.1853.1369012338.3114.python-list@python.org> (permalink)

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On 05/19/2013 07:36 PM, killybeard91@gmail.com wrote:
> One more question. Function np.argmax returns max of non-complex numbers ?
> Because FFT array of my signal is complex.
>

It'd be easier to track the thread if you actually replied to the 
message you're responding to, and also if you included some context. 
But I'll paste the latter in here:

Terry Reedy said:
 > Compute the magnitude spectrum:

 >>> spect = abs(np.fft.fft(x)[:25])
 >>> spect
 > array([  0.        ,  31.85194222,   0.        ,  10.67342282,
 >          0.        ,   6.47213595,   0.        ,   4.69726931,
 >          0.        ,   3.73254943,   0.        ,   3.13762901,
 >          0.        ,   2.7436023 ,   0.        ,   2.47213595,
 >          0.        ,   2.28230601,   0.        ,   2.15105461,
 >          0.        ,   2.06487174,   0.        ,   2.01589594,
 > 0.        ])

 > Find the index of the maximum element:

 >>> np.argmax(spect)
 > 1


Notice that argmax's argument is the result of an abs() call.  It's got 
real numbers representing the magnitude of the various complex numbers.

-- 
DaveA

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Thread

Harmonic distortion of a input signal Anti Log <antilogeffects@gmail.com> - 2013-05-19 03:52 -0700
  Re: Harmonic distortion of a input signal Chris Angelico <rosuav@gmail.com> - 2013-05-20 01:34 +1000
    Re: Harmonic distortion of a input signal killybeard91@gmail.com - 2013-05-19 15:25 -0700
      Re: Harmonic distortion of a input signal Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-05-19 23:49 +0100
      Re: Harmonic distortion of a input signal Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-19 19:19 -0400
  Re: Harmonic distortion of a input signal killybeard91@gmail.com - 2013-05-19 15:59 -0700
  Re: Harmonic distortion of a input signal killybeard91@gmail.com - 2013-05-19 16:03 -0700
  Re: Harmonic distortion of a input signal killybeard91@gmail.com - 2013-05-19 16:36 -0700
    Re: Harmonic distortion of a input signal Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-05-20 13:09 +1200
    Re: Harmonic distortion of a input signal Dave Angel <davea@davea.name> - 2013-05-19 21:11 -0400
      Re: Harmonic distortion of a input signal jmfauth <wxjmfauth@gmail.com> - 2013-05-20 10:23 -0700
        Re: Harmonic distortion of a input signal Christian Gollwitzer <auriocus@gmx.de> - 2013-05-20 19:50 +0200
          Re: Harmonic distortion of a input signal Christian Gollwitzer <auriocus@gmx.de> - 2013-05-20 19:56 +0200
            Re: Harmonic distortion of a input signal jmfauth <wxjmfauth@gmail.com> - 2013-05-23 04:44 -0700
        Re: Harmonic distortion of a input signal Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-05-21 15:58 +0100

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