LOG replaces the contents of the result variable with the natural logarithm of each element of the input vector. LOG10 replaces the contents of the result variable with the base 10 logarithm of each element of the input vector. If an element of the input vector is "missing data" (Represented by "." or "NaN"), taking the log of that element results in NaN. Taking the LOG or LOG10 of zero or of a negative number is an error. 
COPY (1 2.5 3.7) A LOG A B PRINT A B The above program produces the following output: A: (1.0 2.5 3.7) B: (0.0 0.9162907318741551 1.308332819650179)
