Computes ln(1+y) accurately.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <math.h>

      double log1p  (double y);

      float log1pf  (float y);

      long double log1pl  (long double y);

  Additional Information (explode) :

• Argument
• Description
• Return Values