fastcosf: fast single precision Cosine

• Weak alias: cosf
• C Prototype:
  • float fastcosf (float x);
  • Inputs:
    • float x - the single precision input value.
  • Outputs:
    • Single precision Cosine of x.
• Fortran Function Interface:
  • REAL FASTCOSF(X)
  • Inputs:
    • REAL X - the single precision input value.
  • Return Value:
    • Cosine of X.
• Notes:
  • fastcosf computes the single precision Cosine function of its argument x.
    
    This is a relaxed version of cosf, suitable for use with fastmath compiler flags or applications not requiring full error handling. Denormal inputs may produce unpredictable results. Error inputs produce C99 return values. The routine is accurate to better than 1 ulp over most of the valid input range.
• Special case return values:

  • Input	Output
    QNaN	same QNaN
    SNaN	same NaN converted to QNaN
    +infinity	QNaN
    -infinity	QNaN

• Performance:
  • 91 cycles for most valid inputs < 5e5.