The B-spline basis function is given by one recursive formula. However，I hope to obtain popular expression: a0x^n + a1x^(n-1) + ... + an. From the answer How to build a recursive spline function in C++, it seems that Piegl's algorithm can do that. Can anyone give more information about the algorithm?
If you do not have access to the NURBS book by Piegl, then you might look at An Introduction to Polar Forms by Hans-Peter Seidel on pp 38-46 of the 1993 IEEE Computer Graphics & Applications. He diagrams the B-spline computations for the polar form, from which the polynomial coefficient form is a routine conversion.
Let me offer one more reference to an excellent expositor, Phillip J. Schneider, in his paragraph on defining the basis functions. Www.mactech.com/articles/develop/issue_25/schneider.html