MATLAB: Plot 1st order bessel derivative

Question

Hi all,

Can i ask if somebody can help me on why i got 'matrix dimension don't agree' thereby cannot get a plot for first order bessel derivative.

If i type 'diff(besselj(1,z),z)', i'd get 'besselj(0, z) – besselj(1, z)/z'

but then when i want to plot 'besselj(0, z) – besselj(1, z)/z' by typing:

format long
z = (0:1:100)';
a=besselj(0, z) - besselj(1, z)/z;
plot(z,a)

it'd give error as below:

??? Error using ==> minus
Matrix dimensions must agree.
Error in ==> Untitled at 4
a=besselj(0, z) - besselj(1, z)/z;

for some reason the second term gives 101×101 dimension which doesnt agree with the first term (101×1).

Answer 1

I think you need to use element-wise division with the z:

a=besselj(0, z) - besselj(1, z)./z;