ABL Reference

Calculates the logarithm of an expression using a specified base and returns that logarithm as a DECIMAL value.

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.

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 NO-UNDO FORMAT ">>>,>>>.9999". DEFINE VARIABLE number AS DECIMAL NO-UNDO. 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. |

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.

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