Contents

# Using Complex Types in C/C++

As described in the documentation for the Intel®
Visual
Fortran Compiler, C/C++ does not directly implement the Fortran types
COMPLEX(4)
and
COMPLEX(8)
. However, you can write equivalent structures. The type
COMPLEX(4)
consists of two 4-byte floating-point numbers. The first of them is the real-number component, and the second one is the imaginary-number component. The type
COMPLEX(8)
is similar to
COMPLEX(4)
except that it contains two 8-byte floating-point numbers.
Intel® oneAPI Math Kernel Library
provides complex types
MKL_Complex8
and
MKL_Complex16
, which are structures equivalent to the Fortran complex types
COMPLEX(4)
and
COMPLEX(8)
, respectively. The
MKL_Complex8
and
MKL_Complex16
types are defined in the
mkl_types.h
header file. You can use these types to define complex data. You can also redefine the types with your own types before including the
mkl_types.h
header file. The only requirement is that the types must be compatible with the Fortran complex layout, that is, the complex type must be a pair of real numbers for the values of real and imaginary parts.
For example, you can use the following definitions in your C++ code:
``#define MKL_Complex8 std::complex<float>``
and
``#define MKL_Complex16 std::complex<double>``
See Example "Calling a Complex BLAS Level 1 Function from C++" for details. You can also define these types in the command line:
```
-DMKL_Complex8="std::complex<float>"
-DMKL_Complex16="std::complex<double>"
```

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