# Difference between revisions of "LOG"

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The LOG math function returns the natural logarithm of a specified numerical value.

Syntax: logarithm = LOG(value)

• Value parameter MUST be greater than 0! "Illegal function call" error using negative or zero values!
• The natural logarithm is the logarithm to the base e = 2.718282 (approximately).
• The natural logarithm of a is defined as the integral from 1 to a of dx/x.
• Returns are default SINGLE precision unless the value parameter uses DOUBLE precision.

Example 1: FUNCTION to find the base ten logarithm of a numerical value.

FUNCTION Log10#(value AS DOUBLE) STATIC Log10# = LOG(value) / LOG(10.#) END FUNCTION

Explanation: The natural logarithm of the value is divided by the base 10 logarithm. The LOG of ten is designated as a DOUBLE precision return by using # after the Log10 value. The return tells you the number of times 10 goes into a value.

Example 2: A binary FUNCTION to convert INTEGER values using LOG to find the number of digits the return will be.

FUNCTION BIN\$ (n&) IF n& < 0 THEN EXIT FUNCTION 'positive numbers only! negative error! FOR p% = 0 TO INT(LOG(n& + .1) / LOG(2)) ' added +.1 to get 0 to work IF n& AND 2 ^ p% THEN s\$ = "1" + s\$ ELSE s\$ = "0" + s\$ 'find bits on NEXT p% IF s\$ = "" THEN BIN\$ = "&B0" ELSE BIN\$ = "&B" + s\$ 'check for zero return END FUNCTION

Explanation: The LOG of a positive INTEGER value is divided by the LOG of 2 to determine the number of binary digits that will be returned. The FOR loop compares the value with the exponents of two and determines if a bit is ON or OFF as "1" or "0".

See also:

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