float_set

Create a float from an exponent and mantissa

Concepts

• Floating Point Numbers (XFL)

Behaviour

• Compute an XFL (xls17) floating point from the provided exponent and mantissa
• Return that XFL as an int64_t

Definition

C

int64_t float_set (
    int32_t exponent,
    int64_t mantissa
);

Example

C

int64_t small_amount =
  float_set(-81, 1);

Parameters

Name	Type	Description
exponent	int32_t	An exponent in the range -96 to 80
mantissa	int64_t	A mantissa. If negative then the sign of the float is negative.

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Caution

When setting a mantissa that is greater or fewer than 16 decimal digits the exponent will be adjusted to ensure the mantissa is exactly 16 digits. This adjustment may result in an INVALID_FLOAT in some circumstances.

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Special case

XFL canonical 0 is also 0 in the enclosing number. Thus there is never a need to call float_set(0,0);

Return Code

Type	Description
int64_t	The XFL (xls17) enclosing number If negative, an error: INVALID_FLOAT - The adjustment of the mantissa to 16 digits produced an under or overflow.