Chris@19: Previous: Overview of Fortran interface, Chris@19: Up: Overview of Fortran interface Chris@19:
Chris@19: If FFTW is compiled in long double (extended) precision
Chris@19: (see Installation and Customization), you may be able to call the
Chris@19: resulting fftwl_ routines (see Precision) from Fortran if
Chris@19: your compiler supports the C_LONG_DOUBLE_COMPLEX type code.
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Because some Fortran compilers do not support
Chris@19: C_LONG_DOUBLE_COMPLEX, the fftwl_ declarations are
Chris@19: segregated into a separate interface file fftw3l.f03, which you
Chris@19: should include in addition to fftw3.f03 (which declares
Chris@19: precision-independent ‘FFTW_’ constants):
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use, intrinsic :: iso_c_binding Chris@19: include 'fftw3.f03' Chris@19: include 'fftw3l.f03' Chris@19:Chris@19:
We also support using the nonstandard __float128
Chris@19: quadruple-precision type provided by recent versions of gcc on
Chris@19: 32- and 64-bit x86 hardware (see Installation and Customization),
Chris@19: using the corresponding real(16) and complex(16) types
Chris@19: supported by gfortran. The quadruple-precision ‘fftwq_’
Chris@19: functions (see Precision) are declared in a fftw3q.f03
Chris@19: interface file, which should be included in addition to
Chris@19: fftw3l.f03, as above. You should also link with
Chris@19: -lfftw3q -lquadmath -lm as in C.
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