# Scipy.signal.iirfilter equivalent in DSP.jl and more

**URL:** <https://discourse.julialang.org/t/scipy-signal-iirfilter-equivalent-in-dsp-jl-and-more/110783>\
**Category:** Signal and Image Processing\
**Created:** [February 26, 2024, 2:44pm UTC](https://discourse.julialang.org/t/scipy-signal-iirfilter-equivalent-in-dsp-jl-and-more/110783 "2024-02-26T14:44:02Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![scelles](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/scelles/32/220408_2.png) [@scelles](https://discourse.julialang.org/u/scelles)\
**Post date:** [February 26, 2024, 8:46pm UTC](https://discourse.julialang.org/t/scipy-signal-iirfilter-equivalent-in-dsp-jl-and-more/110783/4 "2024-02-26T20:46:15Z")

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One problem of the current implementation can be shown here (input signal is rolling)

![image](https://global.discourse-cdn.com/julialang/original/3X/1/8/18cf034f1f6dfc9207b0673cbbf02fe15d6c6872.png)

orange signal (filtered signal) starts from 0, it should start from it’s previous value (so nearer from -1).

filter should “keep” an internal state

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