Natural Logarithm Function

Computes the base e natural logarithm of x.

If x is 0, ln(x) is –∞. If x is not complex and is less than 0, ln(x) is NaN.
Note For very small values of x, the Natural Logarithm (Arg +1) function is more accurate than adding 1 to x then using this function.

The connector pane displays the default data types for this polymorphic function.


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Inputs/Outputs

  • cdbl.png x —

    x can be a scalar number, array or cluster of numbers, array of clusters of numbers, and so on.

  • idbl.png ln(x) —

    ln(x) is of the same numeric representation as x. When x is of the form x = a + bi, that is, when x is complex, the following equation defines the natural logarithm ln(x): ln(x) = ln(|x|) + i arg(x)where arg(x) is the phase of x over the interval . In other words, LabVIEW uses the following equation:

    • When you wire matrix data as an input to this function, a VI that includes subVIs that work with the matrix data type replaces the function. The resulting VI has the same icon but contains a matrix-specific algorithm. The node remains a VI if you disconnect the matrix from the input(s). Wire other data types as inputs to restore the original function. If you wire a data type to a function and that data type causes a basic math operation to fail, the function returns an empty matrix or NaN.

    Refer to the Matrix Logarithm VI for more information.

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Mathematics\Elementary & Special Functions\Exponential Functions\Exponential.vi