# Derivative of Bessel Function in Matlab

1. ## Derivative of Bessel Function in Matlab

hi there,

i'd like to know how to get the derivative of first kind Bessel Function and the derivative of second kind of Bessel function in Matlab.

Thanks!

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2. ## Derivative of Bessel Function in Matlab

Do you need to obtain symbolic expressions or to perform numerical calculation?
Regards
Z

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3. ## Derivative of Bessel Function in Matlab

I need to perform numerical calculation like you said
thanks
CZ

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4. ## Re: Derivative of Bessel Function in Matlab

See http://ceta.mit.edu/ceta/comp_spec_func/mcjylv.m
it should calculate the derivative of Bessel of first and second kind!

5. ## Derivative of Bessel Function in Matlab

Hi,

Exact formulas for the derivatives can be obtained symbolically. With symbolic toolbox in Matlab, the following lines give it for the first kind (put besselk for the second kind):

syms z;
syms nu;
diff(besselj(nu,z),z)

The results are:

-besselj(nu+1,z)+nu/z*besselj(nu,z)
-besselk(nu+1,z)+nu/z*besselk(nu,z)

(The same can be found in math books or tables.)
Then, use built-in besselj and besselk functions.
I hope this is what you need.
Regards

Z

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6. ## Re: Derivative of Bessel Function in Matlab

Hi zorro,
what if "z" is also a function of two variables, for example, z(x,y)? thanks...

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7. ## Re: Derivative of Bessel Function in Matlab

Hi ozly,

Then the above is still valid.
If what you want are the derivatives with respect to x and y, then apply the chain rule.
Regards

Z

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