# Documentation/Calc Functions/LOG

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## Function name:

LOG

## Category:

Mathematical

## Summary:

Returns the logarithm of a number to the specified base.

## Syntax:

LOG(**Number** [; **Base**])

## Returns:

Returns a real number that is the logarithmic value of the **Number** for the **Base**.

## Arguments:

**Number** is the positive real value or a reference to the cell containing that value whose logarithm is to be calculated.

**Base** (optional) is the positive real value or a reference to the cell containing that value which is the base for the logarithm calculation. If omitted, base 10 is assumed.

If either of the arguments are negative or 0, the function returns an error value.

## Additional details:

The figure below illustrates the LOG function for base-e, base-2 and base-10:

## Examples:

Formula | Description | Returns |
---|---|---|

=LOG(10;3) | the logarithm of 10 base 3 | 2.09590327428938 |

=LOG(7^4;7) | the logarithm of 7 raised to the power 4 with base 7 is itself | 4 |

=LOG(-5;2) | function returns an error value since one of the arguments is negative | Err:502 |

=LOG(5;-2) | function returns an error value since one of the arguments is negative | Err:502 |

## Related LibreOffice functions:

## ODF standard:

## Equivalent Excel functions:

LOG