subroutine chtrfm1(n,x,cosn,iflag)***************************************************** 1-D Chebyshev transform !! MUST call costi(n+1,cosn) to initialize !!***  iflag=1: Spectral  to Physical***  iflag=0: Physical  to Spectral  ***        x: input and output*************************************************      implicit double precision (a-h,o-z)      dimension x(0:n),cosn(1)      if (iflag.eq.1) then         val=.5d0         do i=1,n-1            x(i)=val*x(i)         enddo         call cost(n+1,x,cosn)      else         call cost(n+1,x,cosn)         val=1.d0/n         do i=1,n-1            x(i)=x(i)*val         enddo         x(0)=x(0)*val*.5d0         x(n)=x(n)*val*.5d0      endif      return      end