# Interface Description

All types in this documentation are standard C types: int, float, and double. Fortran 90 users can call the routines with INTEGER, REAL, and DOUBLE PRECISION Fortran types, respectively (see examples in Trigonometric Transform Code Examples in the “Code Examples” Appendix).

The interface description uses the built-in type int for integer values. If you employ the ILP64 interface, read this type as long long int (or INTEGER*8 for Fortran). For more information, refer to the Intel MKL User's Guide.

## Routine Options

All TT routines use parameters to pass various options to one another. These parameters are arrays ipar, dpar and spar. Values for these parameters should be specified very carefully (see Common Parameters). You can change these values during computations to meet your needs.

### Warning

To avoid failure or wrong results, you must provide correct and consistent parameters to the routines.

## User Data Arrays

TT routines take arrays of user data as input. For example, user arrays are passed to the routine d_forward_trig_transform to compute a forward Trigonometric Transform. To minimize storage requirements and improve the overall run-time efficiency, Intel MKL TT routines do not make copies of user input arrays.

### Note

If you need a copy of your input data arrays, save them yourself.

Parent topic: Trigonometric Transform Routines