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obitools3/doc/source/specialvalues.rst
2018-10-21 17:35:18 +02:00

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==============
Special values
==============
NA values
=========
All OBITypes have an associated NA (Not Available) value.
NA values are implemented by specifying an explicit NA value for each type,
corresponding to the R standards as much as possible:
* For the type ``OBIInt_t``, the NA value is ``INT_MIN``.
* For the type ``OBIBool_t``, the NA value is ``2``.
* For the type ``OBIIdx_t`` and ``OBITaxid_t``, the NA value is ``SIZE_MAX``.
* For the type ``OBIChar_t``: the NA value is ``\0``.
* For the type ``OBIFloat_t``::
typedef union
{
double value;
unsigned int word[2];
} ieee_double;
static double NA_value(void)
{
volatile ieee_double x;
x.word[hw] = 0x7ff00000;
x.word[lw] = 1954;
return x.value;
}
Minimum and maximum values for ``OBIInt_t``
===========================================
* Maximum value : ``INT_MAX``
* Minimum value : ``INT_MIN(-1?)``
Infinity values for the type ``OBIFloat_t``
===========================================
* Positive infinity : ``INFINITY`` (should be defined in ``<math.h>``)
* Negative infinity : ``-INFINITY``
NaN value for the type ``OBIFloat_t``
=====================================
* NaN (Not a Number) value : ``NAN`` (should be defined in ``<math.h>`` but probably needs to be tested)