Thread: Plotting Dirac delta function in Mathematica.

Hello,

I'm trying to check my work, but having problems with plotting in Mathematica... Until now i just used Heaviside[ ] function and did ok... but I can't get to plot Dirac... i tried to do it and just can't... please someone help

I'm trying to plot these signals....



and

Originally Posted by sedam7

Hello,

I'm trying to check my work, but having problems with plotting in Mathematica... Until now i just used Heaviside[ ] function and did ok... but I can't get to plot Dirac... i tried to do it and just can't... please someone help

I'm trying to plot these signals....



and

What do you expect the plot to look like? You do know what the Dirac delta is?

CB

Note that in Mathematica,

Originally Posted by Ackbeet

Note that in Mathematica,

But how will M. plot that (if at all), an upward pointing arrow at x=0? Wolfram Alpha certainly does not want to plot it!

CB

Mathematica just shows the axes. There's no line or arrow or anything. Here's a method for plotting the DiracDelta as an arrow:

<<Graphics`Arrow`
PlotOne=Plot[DiracDelta[x-1],{x,0,2}]
PlotTwo=Show[Graphics[Arrow[{1,0},{1,1}]]]
Show[PlotOne,PlotTwo]

That will give you an arrow going from the point <1,0> to the point <1,1>, representing the delta function of "strength" 1.

If you wanted to generalize, you could let

MyDiracDelta[Strength_,a_]=Arrow[{a,0},{a,Strength}]

after loading the arrow package as shown above.

Then you could do

PlotOne=Plot[Strength DiracDelta[x-a],{x,a-1,a+1}]
PlotTwo=Show[Graphics[MyDiracDelta[Strength,a]]]
Show[PlotOne,PlotTwo]

and so on.

Hope that helps.