什么错误

我是在MatlabR2009a中运行的。谢谢帮忙！以下是出现的错误：

Please intput the value of T, tao and Nf
T=10
tao=1
Nf=30
Warning: Explicit integral could not be found.
> In sym.int at 64
  In GTFS_RP at 14
Warning: Explicit integral could not be found.
> In sym.int at 64
  In GTFS_RP at 15
Warning: Explicit integral could not be found.
> In sym.int at 64
  In GTFS_RP at 16
??? Error using ==> sym.double at 29
DOUBLE cannot convert the input expression into a double array.
If the input expression contains a symbolic variable, use the VPA function instead.

Error in ==> GTFS_RP at 17
an(1)=double(vpa(A0,Nn));