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### 8.2.4 Built-in Real (Floating Point) Types

GPC has three built-in floating point types to represent real numbers. Each of them is available under two names (for compatibility to other compilers and languages).

For most purposes, you will always use ``Real'` which is the only one of them that is part of Standard and Extended Pascal. If memory constraints apply, you might want to choose ``ShortReal'` for larger arrays. On the other hand, if high precision is needed, you can use ``LongReal'`. When interfacing with libraries written in other languages such as C, you will need the equivalents for their real types.

Note that not all machines support longer floating point types, so ``LongReal'` is the same as ``Real'` on these machines. Also, some machines may support a longer type, but not do all arithmetic operations (e.g. the ``Sin'` function, section 9.255 Sin) in a precision higher than that of ``Real'`. If you need higher precision, you can look at the ``GMP'` unit (see section 8.14.5 Arithmetic with unlimited size and precision) which provides rational and real numbers with arbitrary precision, but their usage is different from normal real types.

The following real types are guaranteed to be compatible to the real types of GNU C. The sizes given, however, are not guaranteed. They are just typical values used on any IEEE compatible floating point hardware, but they may be different on some machines.

type name | alternative name | GNU C equivalent | size in bits (typically)
`ShortReal` | `Single` | `float` | `32`
`Real` | `Double` | `double` | `64`
`LongReal` | `Extended` | `long double` | `80`

This document was generated by Frank Heckenbach on May, 10 2002 using texi2html