OpenEdge Development:<br />Progress 4GL Reference LOG function

Release 10.1A: OpenEdge Development:
Progress 4GL Reference

LOG function

Calculates the logarithm of an expression using a specified base.

Syntax
LOG ( expression [ , base ] ) 
expression
A decimal expression that you want the logarithm of.
base
A numeric expression that is the base you want to use. If you do not specify a base, LOG returns the natural logarithm, base (e). The base must be greater than 1.
Example

This procedure prompts the user for a base and a number, and then displays the log of the number. The VALIDATE option on the UPDATE statement ensures that the user enters a base value greater than 1 and a number greater than 0.
r-log.p
DEFINE VARIABLE base AS DECIMAL FORMAT ">>>,>>>.9999".
DEFINE VARIABLE number AS DECIMAL.

REPEAT:
  UPDATE base
    VALIDATE(base > 1, "Base must be greater than 1").
  REPEAT:
    UPDATE number
      VALIDATE(number > 0, "Number must be positive").
    DISPLAY number LOG(number, base)
      LABEL "LOG(NUMBER, BASE)".
  END.
END. 
Notes

The LOG function is accurate to approximately 10 decimal places.

After converting the base and exponent to floating-point format, the LOG function uses standard system routines. On some machines, the logarithm routines do not handle large numbers well and might cause your terminal to hang.