Derivative of Bessel Function in Matlab

[txzzc1982]

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!

 

[zorro]

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

 

[txzzc1982]

I need to perform numerical calculation like you said
thanks
CZ

 

[wsalem]

See **broken link removed**
it should calculate the derivative of Bessel of first and second kind!

 

[zorro]

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

 

[ozly]

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

 

[zorro]

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