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Diffstat (limited to 'macros/besself.sci')
| -rw-r--r-- | macros/besself.sci | 41 |
1 files changed, 27 insertions, 14 deletions
diff --git a/macros/besself.sci b/macros/besself.sci index c52f3ac..a6eef80 100644 --- a/macros/besself.sci +++ b/macros/besself.sci @@ -1,15 +1,14 @@ // Copyright (C) 2018 - IIT Bombay - FOSSEE -// // This file must be used under the terms of the CeCILL. // This source file is licensed as described in the file COPYING, which // you should have received as part of this distribution. The terms // are also available at // http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt // Original Source : https://octave.sourceforge.io/signal/ -// Modifieded by:Sonu Sharma, RGIT Mumbai +// Modifieded by: Abinash Singh Under FOSSEE Internship +// Date of Modification: 3 Feb 2024 // Organization: FOSSEE, IIT Bombay // Email: toolbox@scilab.in - function [a, b, c, d] = besself (n, w, varargin) //Bessel filter design. @@ -20,22 +19,17 @@ function [a, b, c, d] = besself (n, w, varargin) //[b, a] = besself (n, [Wl, Wh], "stop") //[z, p, g] = besself (…) //[…] = besself (…, "z") - - //Parameters //n: positive integer value (order of filter) //Wc: positive real value, // 1).Analog 3dB cutoff frequency/frequencies for analog filter, in the range [0, Inf] {rad/sec} // 2).Normalised digital 3dB cutoff frequency/frequencies for digital filter, in the range [0, 1] {dimensionless} - //Description //This function generates a Bessel filter. The default is a Laplace space (s) or analog filter. //If second argument is scalar the third parameter takes in high or low, the default value being low. The cutoff is Wc rad/sec. //If second argument is vector of length 2 ie [Wl Wh] then third parameter may be pass or stop default is pass for bandpass and band reject filter respectively //[z,p,g] = besself(...) returns filter as zero-pole-gain rather than coefficients of the numerator and denominator polynomials. //[...] = besself(...,’z’) returns a discrete space (Z) filter. Wc must be less than 1 {dimensionless}. - - //Examples //[b, a]=besself(2,.3,"high","z") //Output : @@ -46,14 +40,14 @@ function [a, b, c, d] = besself (n, w, varargin) // // 0.4668229 - 0.9336457 0.4668229 // - + // Dependencies + // besselap bilinear sftrans zp2tf funcprot(0); [nargout nargin] = argn(); if (nargin > 4 | nargin < 2 | nargout > 4 | nargout < 2) error("besself: invalid number of inputs") end - // interpret the input parameters if (~ (isscalar (n) & (n == fix (n)) & (n > 0))) error ("besself: filter order N must be a positive integer"); @@ -79,14 +73,13 @@ function [a, b, c, d] = besself (n, w, varargin) error ("besself: expected [high|stop] or [s|z]"); end end - // FIXME: Band-pass and stop-band currently non-functional, remove // this check once low-pass to band-pass transform is implemented. if (~ isscalar (w)) error ("besself: band-pass and stop-band filters not yet implemented"); end - [rows_w colums_w] = size(w); + [rows_w columns_w] = size(w); if (~ ((length (w) <= 2) & (rows_w == 1 | columns_w == 1))) error ("besself: frequency must be given as WC or [WL, WH]"); @@ -115,7 +108,6 @@ function [a, b, c, d] = besself (n, w, varargin) if (digital) [zero, pole, gain] = bilinear (zero, pole, gain, T); end - // convert to the correct output form if (nargout == 2) // a = real (gain * poly (zero)); @@ -127,7 +119,28 @@ function [a, b, c, d] = besself (n, w, varargin) c = gain; else // output ss results - // [a, b, c, d] = zp2ss (zero, pole, gain); + // FIXME : test zp2ss + //[a, b, c, d] = zp2ss (zero, pole, gain); error("besself: yet not implemented in state-space form OR invalid number of o/p arguments") end endfunction + +/* +Note : This function is tested with Octave's outputs as a reference. +# Test input validation +[a, b] = besself () // error passed +[a, b] = besself (1) // error passed +[a, b] = besself (1, 2, 3, 4, 5) // error passed +[a, b] = besself (.5, .2) // error passed +[a, b] = besself (3, .2, "invalid") // error passed + //[b, a] = besself(n, Wc) +[b a] = besself(2,1000) // passed +//[b, a] = besself (n, Wc, "high") +[b a] = besself(7,0.3,"high") // passed +//[b, a] = besself (n, [Wl, Wh]) +[b a] = besself(4,[1000 5000]) // error: besself: band-pass and stop-band filters not yet implemented +//[b, a] = besself (n, [Wl, Wh], "stop") +[b a] = besself(4,[1000 5000],"stop") // besself: band-pass and stop-band filters not yet implemented +//[z, p, g] = besself (…) +[z,p,g] = besself(9,0.8,"high") // passed +*/
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