# pig tutorial - apache pig tutorial - Apache Pig LOG() - pig latin - apache pig - pig hadoop

## What is LOG() function?

• In mathematics, the logarithm is the inverse operation to exponentiation, just as division is the inverse of multiplication and vice versa.
• That means the logarithm of a number is the exponent to which another fixed number, the base, must be raised to produce that number.
• In simple cases the logarithm counts factors in multiplication.
• For example, the base 10 logarithm of 1000 is 3, as 10 to the power 3 is 1000 (1000 = 10 × 10 × 10 = 10^3); 10 is used as a factor three times. Learn Apache Pig - Apache Pig tutorial - Apache Pig Log - Apache Pig examples - Apache Pig programs

## LOG() function in Apache Pig

• The LOG() function of Pig Latin is used to calculate the natural logarithm (base e) value of a given expression.
• Returns the natural logarithm (base e) of an expression.

## Example

• Ensure that we have a file named wikitechy_math.txt in the HDFS directory /pig_data/.
• This file contains integer and floating point values as given below.

wikitechy_math.txt

• You have loaded this file into Pig with a relation named math_data as given below.
• Now calculate the log values of the contents of the wikitechy_math.txtfile using LOG() function as given below.

## Verification

• Now verify the contents of the relation using the Dump operator as given below.

## Output

• The above statement stores the result in the relation named log_data.