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Diffstat (limited to 'macros/chirp.sci')
| -rw-r--r-- | macros/chirp.sci | 139 |
1 files changed, 85 insertions, 54 deletions
diff --git a/macros/chirp.sci b/macros/chirp.sci index 41a94e6..c8acdeb 100644 --- a/macros/chirp.sci +++ b/macros/chirp.sci @@ -1,55 +1,86 @@ -function [y] = chirp(t,f0,t1,f1,frm,phse) -//This function evaluates a chirp signal at time t. -//Calling Sequence -//y = chirp(t) -//y = chirp(t, f0) -//y = chirp(t, f0, t1) -//y = chirp(t, f0, t1, f1) -//y = chirp(t, f0, t1, f1, frm) -//y = chirp(t, f0, t1, f1, frm, phse) -//Parameters -//t: vector -//f0: -//t1: -//f1: -//frm: string value, takes in "linear", "quadratic", "logarithmic" -//phse: -//Description -//This is an Octave function. -//This function evaluates a chirp signal at time t. A chirp signal is a frequency swept cosine wave. -//The first argument is a vector of times to evaluate the chirp signal, second argument is the frequency at t=0, third argument is time t1 and fourth argument is frequency at t1. -//The fifth argument is the form which takes in values "linear", "quadratic" and "logarithmic", the sixth argument gives the phase shift at t=0. -//Examples -//chirp([4,3,2,1],4,5,0.9) -//ans = -// column 1 to 3 -// 0.9685832 0.2486899 0.0627905 -// column 4 -// - 0.3681246 - -funcprot(0); - -rhs = argn(2) -if(rhs<1 | rhs>6) -error("Wrong number of input arguments.") -end - select(rhs) - case 1 then - y = callOctave("chirp",t) - case 2 then - y = callOctave("chirp",t,f0) - case 3 then - y = callOctave("chirp",t,f0,t1) - case 4 then - y = callOctave("chirp",t,f0,t1,f1) - case 5 then - //if(~(form == "linear" | form == "quadratic" | form == "logarithmic")) - //error("Chirp does not understand that form. Enter linear, quadratic or logarithmic.") - //else - y = callOctave("chirp",t,f0,t1,f1,frm) - //end - case 6 then - y = callOctave("chirp",t,f0,t1,f1,frm,phse) - end +// 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 +// Organization: FOSSEE, IIT Bombay +// Email: toolbox@scilab.in + +function [y] = chirp(t,f0,t1,f1,form,phase) + //This function evaluates a chirp signal at time t. + + //Calling Sequence + //y = chirp(t) + //y = chirp(t, f0) + //y = chirp(t, f0, t1) + //y = chirp(t, f0, t1, f1) + //y = chirp(t, f0, t1, f1, frm) + //y = chirp(t, f0, t1, f1, frm, phse) + + //Parameters + //t: a vector of times to evaluate the chirp signal + //f0: the frequency at t=0 [default value = 0 Hz] + //t1: some intermediate time [default value = 1 sec] + //f1: frequency at t1. [default value = 100 Hz] + //frm: string value, takes in "linear", "quadratic", "logarithmic" [default value = "linear"] + //phse: phase shift at t=0. [default value = 0] + //y: chirp signal value corresponding to t. + + //Description + //This function evaluates a chirp signal at time t. A chirp signal is a frequency swept cosine wave. + //The first argument is a vector of times to evaluate the chirp signal, second argument is the frequency at t=0, third argument is time t1 and fourth argument is frequency at t1. + //The fifth argument is the form which takes in values "linear", "quadratic" and "logarithmic", the sixth argument gives the phase shift at t=0. + + //Examples + //t = [4,3,2,1]; + //f0 = 4; + //t1 = 5; + //f1 = 0.9; + //form = "quadratic"; + //y = chirp(t, f0, t1, f1, form) + //Output : + // y = + // + // - 0.6112508 0.7459411 - 0.4854201 0.9664658 + + funcprot(0); + [nargout,nargin]=argn(0); + + if nargin < 1 | nargin > 6 + error("chirp: invalid number of inputs"); + end + if nargin < 2, f0 = []; end + if nargin < 3, t1 = []; end + if nargin < 4, f1 = []; end + if nargin < 5, form = []; end + if nargin < 6, phase = []; end + + if isempty(f0), f0 = 0; end + if isempty(t1), t1 = 1; end + if isempty(f1), f1 = 100; end + if isempty(form), form = "linear"; end + if isempty(phase), phase = 0; end + + phase = 2*%pi*phase/360; + + if (form== "linear") + a = %pi*(f1 - f0)/t1; + b = 2*%pi*f0; + y = cos(a*t.^2 + b*t + phase); + elseif (form== "quadratic") + a = (2/3*%pi*(f1-f0)/t1/t1); + b = 2*%pi*f0; + y = cos(a*t.^3 + b*t + phase); + elseif (form== "logarithmic") + a = 2*%pi*t1/log(f1-f0); + b = 2*%pi*f0; + x = (f1-f0)^(1/t1); + y = cos(a*x.^t + b*t + phase); + else + error(sprintf("chirp: chirp doesnt understand ''%s''",form)); + end endfunction - |