Vector Log Natural (LN)

Summary

Element-wise natural logarithm of the input series.

Chart

Reference data (CSV) · Chart (SVG)

Chart metadata i

Outputs

• outReal: line · zero · positive · negative

Formula

outReal[i] = log(inReal[i])

Notes

• The logarithm is defined only for positive values: a negative input gives NaN, and a zero input gives negative infinity.

Inputs

• inReal — Input value series

Outputs

• outReal — Natural log of each input value

Properties

Numerical Stability: Start-Independent

☐ Overlap Input
✅ Independent Y-Axis i
☐ Candlestick
☐ Display Shift

✅ Can Output NaN or ±Inf i
☐ Identity at Period 1
✅ Uses Transcendental i
✅ Input Must Be Positive i

Example

C

#include <stdio.h>
#include <ta_libc.h>

int n = 252;
double series[252]; /* your data, oldest first */
double out[252];
int outBegIdx, outNBElement;

TA_Initialize();
TA_LN( 0, n - 1, series, &outBegIdx, &outNBElement, out );
printf( "%d values from bar %d; last out = %f\n", outNBElement, outBegIdx, out[outNBElement - 1] );

Rust

use ta_lib::Core;

let series = vec![0.0; 252]; // your data, oldest first
let mut out = vec![0.0; 252];

let core = Core::new();
let range = core.ln(0, series.len() - 1, &series, &mut out)?;
println!("{} values from bar {}; last out = {}", range.count, range.beg_idx, out[range.count - 1]);

Java

import io.github.talib.Core;
import io.github.talib.OutRange;

double[] series = new double[252]; // your data, oldest first
double[] out = new double[252];

Core core = Core.DEFAULT;
OutRange r = core.ln(0, series.length - 1, series, out);
System.out.println(r.count() + " values from bar " + r.begIdx() + "; last out = " + out[r.count() - 1]);

C#

using System;
using TALib;

var series = new double[252]; // your data, oldest first
var outReal = new double[252];

var core = Core.Default;
OutRange r = core.Ln(0, series.Length - 1, series, outReal);
Console.WriteLine($"{r.Count} values from bar {r.BegIdx}; last outReal = {outReal[r.Count - 1]}");

TypeScript

import { ln } from 'ta-lib';

const series = new Float64Array(252); // your data, oldest first

const { begIdx, values } = ln(series);
console.log(values.length + ' values from bar ' + begIdx + '; last values = ' + values[values.length - 1]);

Implementation

Added in 0.4.0.

TA-Lib Definition: ln.c · ln.yaml

Native	File
C	ta_LN.c
Rust	ln.rs
Java	Core_LN.java
C#	Core_LN.cs
TypeScript	ln.ts

Python: talib.LN, see ta-lib-python.

TA-Lib is also available for R and more using a wrapper.

Aliases

Natural Log, Vector Log Natural, Log

See Also

LOG10 · EXP · SQRT

References

• Wikipedia, Natural logarithm: en.wikipedia.org/wiki/Natural_logarithm