tailieunhanh - Advanced Mathematical Methods for Scientists and Engineers Episode 4 Part 2

Tham khảo tài liệu 'advanced mathematical methods for scientists and engineers episode 4 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Example Consider a series expansion about the origin of the equation The indicial equation is w ------ w ----- w 0. z z2 a2 - 1 0 a 1. Substituting a Frobenius series into the differential equation z n a n a 1 anz z z n a anz anz 0 n 0 n 0 n 0 n a n a 1 anz n a anz n a 1 ữn iz anz 0 n 0 n 0 n 1 n 0 a a 1 a 1 ao n 1 n a n a 1 an n a 1 an n a 1 an 1 zn 0. Equating powers of z to zero an a an 1 a n a 1 We know that the first solution has the form w1 z anzn. n 0 Setting a 1 in the reccurence formula _ an 1 _ 2ao ữn n 2 n 2 . 1214 Thus the first solution is E2au n -- n 2 n u v 7 1 . -n 2 2au1 V . z z n 2 n u v 7 210 ez-1 - z . Now to find the second solution. Setting a 1 in the reccurence formula an an-1 _ au n n . We see that in this case there is no trouble in defining a2 a2 . The second solution is W2 au zn au z J ez z z n z n u Thus we see that the general solution is w ez 1 z -2 ez zz w i ez d J 1 1 . zz .

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