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| <h5 class="subsubsection">A.5.3.3 IEEE Floating Point</h5> |
| |
| <p><a name="index-IEEE-floating-point-representation-3810"></a><a name="index-floating-point_002c-IEEE-3811"></a> |
| Here is an example showing how the floating type measurements come out |
| for the most common floating point representation, specified by the |
| <cite>IEEE Standard for Binary Floating Point Arithmetic (ANSI/IEEE Std |
| 754-1985)</cite>. Nearly all computers designed since the 1980s use this |
| format. |
| |
| <p>The IEEE single-precision float representation uses a base of 2. There |
| is a sign bit, a mantissa with 23 bits plus one hidden bit (so the total |
| precision is 24 base-2 digits), and an 8-bit exponent that can represent |
| values in the range -125 to 128, inclusive. |
| |
| <p>So, for an implementation that uses this representation for the |
| <code>float</code> data type, appropriate values for the corresponding |
| parameters are: |
| |
| <pre class="smallexample"> FLT_RADIX 2 |
| FLT_MANT_DIG 24 |
| FLT_DIG 6 |
| FLT_MIN_EXP -125 |
| FLT_MIN_10_EXP -37 |
| FLT_MAX_EXP 128 |
| FLT_MAX_10_EXP +38 |
| FLT_MIN 1.17549435E-38F |
| FLT_MAX 3.40282347E+38F |
| FLT_EPSILON 1.19209290E-07F |
| </pre> |
| <p>Here are the values for the <code>double</code> data type: |
| |
| <pre class="smallexample"> DBL_MANT_DIG 53 |
| DBL_DIG 15 |
| DBL_MIN_EXP -1021 |
| DBL_MIN_10_EXP -307 |
| DBL_MAX_EXP 1024 |
| DBL_MAX_10_EXP 308 |
| DBL_MAX 1.7976931348623157E+308 |
| DBL_MIN 2.2250738585072014E-308 |
| DBL_EPSILON 2.2204460492503131E-016 |
| </pre> |
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