# BigInteger.Log Method (BigInteger, Double)

.NET Framework 4.6 and 4.5

Returns the logarithm of a specified number in a specified base.

Namespace:  System.Numerics
Assemblies:   System.Runtime.Numerics (in System.Runtime.Numerics.dll)
System.Numerics (in System.Numerics.dll)

## Syntax

```public static double Log(
BigInteger value,
double baseValue
)
```

#### Parameters

value
Type: System.Numerics.BigInteger

A number whose logarithm is to be found.

baseValue
Type: System.Double

The base of the logarithm.

#### Return Value

Type: System.Double
The base baseValue logarithm of value, as shown in the table in the Remarks section.

## Exceptions

ExceptionCondition
ArgumentOutOfRangeException

The log of value is out of range of the Double data type.

## Remarks

The value and baseValue parameters are specified as base 10 numbers.

The precise return value of the method depends on the sign of value and on the sign and value of baseValue, as the following table shows.

value parameter

baseValue parameter

Return value

value > 0

(0 < baseValue < 1) -or-(baseValue > 1)

logbaseValue(value)

value < 0

(any value)

(any value)

baseValue < 0

Double.NaN

value != 1

baseValue = 0

Double.NaN

value != 1

baseValue = Double.PositiveInfinity

Double.NaN

(any value)

baseValue = Double.NaN

Double.NaN

(any value)

baseValue = 1

Double.NaN

value = 0

0 < baseValue < 1

Double.PositiveInfinity

value = 0

baseValue > 1

Double.PositiveInfinity

value = 1

baseValue = 0

0

value = 1

baseValue = Double.PositiveInfinity

0

To calculate the base 10 logarithm of a BigInteger value, call the Log10 method. To calculate the natural logarithm of a number, call the Log(BigInteger) method.

This method corresponds to the Math.Log method for the primitive numeric types.

## Version Information

#### .NET Framework

Supported in: 4.6, 4.5, 4

Supported in: 4

#### Portable Class Library

Supported in: Portable Class Library
Supported in: Windows Phone 8.1