How to evaluate dirac function in matlab?

Asked by Atta Oveisi

Atta Oveisi (view profile)

on 23 May 2013

I have this problem in matlab 2011a that I can not evaluate dirac function of higher order. In other words, the symbolic expression works well:

```syms x;
diff(dirac(x),x)
```
```ans =
```
```dirac(x, 1)
```

However, it can not evaluate dirac(x, 1) when x is double:

```>> dirac(1, 1)
??? Error using ==> dirac
Too many input arguments.
```

What should I do? Is there any code available ?

I can evaluate this in Maple but it is hard to believe that matlab doesn't prepared for this simple problem.

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Iman Ansari (view profile)

Answer by Iman Ansari

Iman Ansari (view profile)

on 23 May 2013
Edited by Iman Ansari

Iman Ansari (view profile)

on 23 May 2013
```syms x;
y=diff(dirac(x),x)
subs(y,1)
```

Youssef Khmou (view profile)

Answer by Youssef Khmou

Youssef Khmou (view profile)

on 23 May 2013

hi

The dirac function accepts only one argument (at least for earlier versions than yours) however, if you do not have the symbolic toolbox you can program your own function and put "1" in "0" instead of +infinity .

-First solution :

``` t=-10:0.001:10;
y=dirac(t);
figure, plot(t,y);
dy=diff(y)./diff(t);
figure, plot(t(1:end-1),dy,'r')```

-Second solution :

```function z=Dirac(t)
N=length(t);
z=zeros(size(t));
for n=1:N
```
```    if t(n)==0
z(n)=1;
end
end```

Adjust this function for later use ....

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