Convolution Command: Inputs Invalid

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Andrew Cunningham 2018-9-23

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评论： Andrew Cunningham 2018-9-27

I am having trouble getting the output of my two functions to be accepted by the convolution function. Any help is appreciated getting this to work. I get the following when I use conv: Invalid data type. First and second arguments must be numeric or logical. I am familiar with matlab and can do the plots and other aspects once I get the function working. Thank you in advance for any help. I attached my code below:

t = -5:10; syms n x1 = symsum(dirac(t-8.*n),n,0,5); h1 = exp(-t).*heaviside(t); H1 = h1.'; Yt = conv(x1,h1);

My two functions are: x(t)=Sum(from 0-5) dirac(t-8n) h(t)=e^(-t)*u(t)

where u(t) is the step function

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Image Analyst 2018-9-23

Why are you using symbolic variables? Can't you just use numerical values with actual values for the elements?

Andrew Cunningham 2018-9-23

I have “syms n” because it is needed in order to use the symsum to do summation. Cause n is also only from 0 to 5 while the time plot needs to be larger to plot the convolution of the two functions

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Answer 1

Viren Gupta 2018-9-27

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I tried relicating your code. x1 is of type sym. You can convert x1 into numeric type using double(x1). That should solve the error. 'h1' is already a numeric type variable

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Andrew Cunningham 2018-9-27

Awesome thanks! I checked it out and that works. I solved it another way though and used ~isfinite(array) which turned the array into finite values. The only values in the array were infinity and 0 so I lost no data in doing it this way. Thank you for the help!

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