1/*
2
3(d8) THIS PROGRAM REVERSES THE FUNCTION Y EXPRESSED AS
4
5
6A POWER SERIES IN X.  CALL IT WITH
7
8
9                      REV(Y,X,N)
10
11
12WHERE N IS THE TRUNCATION ORDER
13*/
14
15
16rev(y,x,n):=(y:taylor(y,x,0,n),eq:x = sum(b[i]*y^i,i,1,n),
17    sol:solve(makelist(coeff(eq,x,i),i,1,n),makelist(b[i],i,1,n)),y:'y,
18    eq:x = sum(b[i]*y^i,i,1,n),eq:ev(eq,sol))$
19