- #1
yungman
- 5,718
- 241
Attached is a definite integral copy from page 20 of http://ia601507.us.archive.org/5/items/ATreatiseOnTheTheoryOfBesselFunctions/Watson-ATreatiseOnTheTheoryOfBesselFunctions.pdf
It said
[tex]\int_{\alpha}^{2\pi+\alpha}e^{j(n\theta-z\sin\theta)}d\theta[/tex]
I can understand ##\alpha=-\pi## and change the integral to
[tex]\int_{-\pi}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta=\int_{0}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta-\int_{0}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta[/tex]
But I can not agree with changing ##\theta## to ##-\theta## in half of the equation so
[tex]J_n(z)=\int_0^{\pi}\left[e^{j(n\theta-z\sin\theta)}+e^{-j(n\theta-z\sin\theta)}\right]d\theta[/tex]
You cannot just at will, substitute second part of the equation from ##\theta## to ##-\theta## and leave the first part ##\theta## still ##\theta##.
Am I missing the point?
Thanks
It said
[tex]\int_{\alpha}^{2\pi+\alpha}e^{j(n\theta-z\sin\theta)}d\theta[/tex]
I can understand ##\alpha=-\pi## and change the integral to
[tex]\int_{-\pi}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta=\int_{0}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta-\int_{0}^{\pi}e^{j(n\theta-z\sin\theta)}d\theta[/tex]
But I can not agree with changing ##\theta## to ##-\theta## in half of the equation so
[tex]J_n(z)=\int_0^{\pi}\left[e^{j(n\theta-z\sin\theta)}+e^{-j(n\theta-z\sin\theta)}\right]d\theta[/tex]
You cannot just at will, substitute second part of the equation from ##\theta## to ##-\theta## and leave the first part ##\theta## still ##\theta##.
Am I missing the point?
Thanks
Attachments
Last edited: