CC78K4 Datasheet, PDF (269/523 Pages) NEC – CC78K4 Ver.2.30 or Later, C Compiler Language

CHAPTER 10 LIBRARY FUNCTIONS
7-37 logf
Mathematical Functions
FUNCTION
logf finds the natural logarithm.
HEADER
math.h
FUNCTION PROTOTYPE
float logf (float x);
Function
logf
Arguments
x ... Numeric value to perform
operation
Return Value
Normal ... Natural logarithm of x
When x is non-numeric ... NaN
When x is infinite ... +∞
When x ≤ 0 ... HUGE_VAL
(with negative sign)
EXPLANATION
• Finds natural logarithm of x.
• If x is non-numeric, NaN is returned.
• If x is +∞, +∞ is returned.
• In the case of an area error of x < 0, HUGE_VAL with a negative sign is returned, and EDOM is set to errno.
• If x = 0, HUGE_VAL with a negative sign is returned, and ERANGE is set to errno.
User’s Manual U15556EJ1V0UM
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