FLNP1 f-l-n-p-one FLOATING EXT

( F: r1 -- r2 ) or ( r1 -- r2 )

r2 is the natural logarithm of the quantity r1 plus one. An ambiguous condition exists if r1 is less than or equal to negative one.



This function allows accurate compilation when its arguments are close to zero, and provides a useful base for the standard logarithmic functions. For example, FLN can be implemented as:

: FLN 1.0E0 F- FLNP1 ;