https://youtu.be/eQBg2hsqJjQ
legendre differential equation
https://youtu.be/X_7qyIRJt0k
bessel differential equation
https://youtu.be/TGCNnSvumbg
recurrence formulae. (. 3,4 )
https://youtu.be/kekigsr3rC8
generating function of Jn (x)
https://youtu.be/OYSlF-SOMDs
diagonalization of matrix
https://youtu.be/4Zo6YM6fwTU
eigenvalue and eigenvector
https://youtu.be/JaUc1pP8bpk
laguerres differential equations
https://youtu.be/X_7qyIRJt0k
bessel differential equation
