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## Plot Problem

**From**: |
Thomas D. Dean |

**Subject**: |
Plot Problem |

**Date**: |
Sun, 6 Aug 2017 12:09:00 -0700 |

**User-agent**: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 |

`I have a problem where plot seems to run forever. At least for three
``minutes.
`
octave 4.3.0+. Signal 1.3.2
A web example:
https://p5r.uk/blog/2009/filters-with-gnu-octave.html
% The sampling frequency in Hz.
Fsam = 1500;
% Nyquist frequency, in Hz.
% The Nyquist frequency is half your sampling frequency.
Fnyq = Fsam/2;
% The cut-off frequency of your Low pass filter in Hz.
% This frequency must be greater than 0 and less than Fnyq.
Fc=1/4;
% Create a first-order Butterworth low pass.
% The returned vectors are of legth n.
% Thus a first order filter is created with n = 2.
[b,a]=butter(2, Fc/Fnyq);
% Create a 5 seconds signal with 3 components:
% a 1 Hz and a 200 Hz sinusoidal component and some gaussian noise.
t=0:1/Fsam:5;
x=sin(2*pi*t) + sin(2*pi*200*t) + randn(size(t));
% Apply the filter to the input signal and plot input and output.
y=filter(b,a,x);
plot(t, [x; y])
m1 = abs(fft(x));
m2 = abs(fft(y))
subplot(2,1,1); plot(m1); ## OK
subplot(2,1,2); plot(m2); ## OK
close
plot([m1;m2]); ## seems to hang forever
What am I doing wrong?
Tom Dean

**Plot Problem**,
*Thomas D. Dean* **<=**