CIGAL Reference Manual, Chapter 0 (log):
usage: result = log(x)
The LOG function returns the logarithm of its argument (base 10). If the input value is too large (>= 13) the routine returns 0. If the input X is a variable with more than one value, LOG will generate an output variable of logarithms with the same number of values.
See Also:
ALOG(3)