There are four extensions to the standard FFTPACK and VFFTPACK libraries. First, Sun Performance Library contains double precision and double complex transforms. Subroutines to process double precision and double complex data are not available with the standard package from Netlib, so calls to these subroutine may not be portable. Second, multidimensional FFTs have been added. Third, convolution and correlation subroutines have been added. Finally, this version of Sun Performance Library contains a native C/C++ interface to FFTPACK and VFFTPACK. Conventions for this interface are described in detail in the preface to this manual.