log

Natural logarithm

Syntax

Y = log(X)

Description

Y= log(X)returns the natural logarithmln(x)of each element in arrayX.

Thelogfunction’s domain includes negative and complex numbers, which can lead to unexpected results if used unintentionally. For negative and complex numbersz = u + i*w, the complex logarithmlog(z)returns

log(abs(z)) + 1i*angle(z)

If you want negative and complex numbers to return error messages rather than return complex results, userealloginstead.

Examples

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Natural Logarithm of Negative Number

Open Live Script

Show that the natural logarithm of -1 is $i π$ .

log(-1)

ans = 0.0000 + 3.1416i

Input Arguments

collapse all

`X`—Input array
scalar|vector|matrix|multidimensional array

Input array, specified as a scalar, vector, matrix, or multidimensional array.

Data Types:single|double
Complex Number Support:Yes

Output Arguments

collapse all

`Y`— Logarithm values
scalar | vector | matrix | multidimensional array

Logarithm values, returned as a scalar, vector, matrix, or multidimensional array.

For positive real values ofXin the interval (0,Inf),Yis in the interval (-Inf,Inf). For complex and negative real values ofX,Y是复杂的。The data type ofYis the same as that ofX.

Extended Capabilities

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

This function fully supports tall arrays. For more information, seeTall Arrays.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

When the input valuexis real, but the output should be complex, simulation ends with an error. To produce the complex result, make the input value complex by passing incomplex(x).

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Usage notes and limitations:

When the input valuexis real, but the output should be complex, simulation ends with an error. To produce the complex result, make the input value complex by passing incomplex(x).

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Usage notes and limitations:

If the output of the function running on the GPU can be complex, then you must explicitly specify its input arguments as complex. For more information, seeWork with Complex Numbers on a GPU(Parallel Computing Toolbox).

For more information, seeRun MATLAB Functions on a GPU(Parallel Computing Toolbox).

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, seeRun MATLAB Functions with Distributed Arrays(Parallel Computing Toolbox).

MATLAB Documentation

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log

Syntax

Description

Examples

Natural Logarithm of Negative Number

Input Arguments

X—Input arrayscalar|vector|matrix|multidimensional array

Output Arguments

Y— Logarithm valuesscalar | vector | matrix | multidimensional array

Extended Capabilities

Tall ArraysCalculate with arrays that have more rows than fit in memory.

C/C++ Code GenerationGenerate C and C++ code using MATLAB® Coder™.

GPU Code GenerationGenerate CUDA® code for NVIDIA® GPUs using GPU Coder™.

GPU ArraysAccelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed ArraysPartition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

See Also

MATLAB Documentation

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`X`—Input array
scalar|vector|matrix|multidimensional array

`Y`— Logarithm values
scalar | vector | matrix | multidimensional array

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.