Matlab example: two expressions of step function

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Preface

The step function is MATLAB There are two kinds of calling functions ：
heaviside() function 、stepfun() function
Now let's take a look at the difference and usage between them .

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One 、heaviside() function

1.heaviside() Function introduction

Here's the picture MATLAB The introduction in the dictionary , Can see heaviside Function call is very simple ：H = heaviside(x); also heaviside It's a Discontinuous functions . It returns 0 Express x < 0, return 1/2 Express x = 0, return 1 Express x > 0.

Simple painting heaviside

syms x
fplot(heaviside(x), [-2, 2])

2.heaviside() example

The code is as follows

>> T=0.01;% step 
>> t1=0;t2=3;t3=-2;t4=2;% Coordinate parameters 
>> t5=t1:T:t2;%t5 Value range ;
>> t6=t3:T:t4;%t6 Value range ;
>> f1=2*exp(-2*t5);% Exponential function 
>> f2=3*(heaviside(t6-1)-heaviside(t6-2));% Gate function 
>> [y]=conv(f1,f2);% Set convolution as matrix 
>> y=y*T;t=(t1+t3):T:(t2+t4);% The value range of convolution 
>> subplot(3,1,1);plot(t5,f1,'r');axis([(t1+t3),(t2+t4),min(f1),max(f1)+0.5]);% Set axis 
>>  ylabel('f1(t) The index curve ');line([0,0],[0,2.5]);title(' Signal convolution ');
>>  subplot(3,1,2);plot(t6,f2);axis([(t1+t3),(t2+t4),min(f2),max(f2)+0.5]);
>> ylabel('f2(t) Gate function ');
>> subplot(3,1,3);plot(t,y,'m');axis([(t1+t3),(t2+t4),min(y),max(y)+0.5]);ylabel('y(t) Convolution synthesis curve ');

Two 、stepfun() function

1.stepfun() Function introduction

stepfun Function call stepfun(x,y) among x Represents abscissa and y Represents the ordinate . among x It must be an ascending vector , y Length ratio of x Big 1.
A simple example

The code is as follows （ Example ）：

>> b=-5:0.01:20;% Define time samples 
>> b0=0;% The moment when the signal changes 
>> ut=stepfun(b,b0);% Generate unit step signal 
>> plot(b,ut),axis([-5,20,-2.5,10])% Axis 

2.stepfun() example

The code is as follows （ Example ）：

>> T=0.01;% step 
>> t1=0;t2=3;t3=-2;t4=2;% Coordinate parameters 
>> t5=t1:T:t2;%t5 Value range ;
>> t6=t3:T:t4;%t6 Value range ;
>> f1=2*exp(-2*t5);% Exponential function 
>> f2=3*(stepfun(t6,-1)-stepfun(t6,2));% Gate function 
>> [y]=conv(f1,f2);% Set convolution as matrix 
>> y=y*T;t=(t1+t3):T:(t2+t4);% The value range of convolution 
>> subplot(3,1,1);plot(t5,f1,'r');axis([(t1+t3),(t2+t4),min(f1),max(f1)+0.5]);% Set axis 
>> ylabel('f1(t) The index curve ');line([0,0],[0,2.5]);title(' Signal convolution ');
>> subplot(3,1,2);plot(t6,f2);axis([(t1+t3),(t2+t4),min(f2),max(f2)+0.5]);
>> ylabel('f2(t) Gate function ');
>> subplot(3,1,3);plot(t,y,'m');axis([(t1+t3),(t2+t4),min(y),max(y)+0.5]);ylabel('y(t) Convolution synthesis curve ');

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summary

That's what we're going to talk about today , This article only briefly introduces heaviside() function 、stepfun() function Use , and MATLAB Provides a large number of functions and methods that enable us to process data quickly and conveniently , Are waiting for our exploration and use .

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