Engineering

IMLN Function in Excel

Returns the natural logarithm of a complex number.

Syntax

  • =IMLN(inumber)

Arguments

  • inumber (required): Complex number

Examples

  • =IMLN("1+i") - Natural log of complex - Result: 0.347+0.785i

IMLN in technical sheets

  • Document units in adjacent cells — many engineering functions require exact unit strings.
  • Use [CONVERT](/functions/convert/) for unit changes before specialized formulas.
  • Validate inputs with [ISNUMBER](/functions/isnumber/) and range checks.

Common errors

  • #NUM! if not valid complex number

Use cases

  • Complex analysis
  • Engineering
  • Mathematics

Frequently asked questions

  • What is the IMLN function in Excel? IMLN returns the natural logarithm of a complex number. The syntax is =IMLN(inumber). Typical use cases include complex analysis, engineering, mathematics.
  • How do I use the IMLN function? To use IMLN, type =IMLN( in a cell and provide the required arguments. Excel will show you the syntax and parameter hints as you type. Make sure to close the parentheses and press Enter to execute the function.
  • Why is IMLN not working in my Excel? Common issues with IMLN include #NUM! if not valid complex number. Start by checking the syntax =IMLN(inumber), then verify each referenced cell or range.

Editorial review

  • Reviewed by Excel.Directory Editorial Team. Updated May 2026.

When to use IMLN

  • Complex analysis — common Engineering scenario for IMLN.
  • Engineering — common Engineering scenario for IMLN.
  • Mathematics — common Engineering scenario for IMLN.

IMLN in the Engineering category

  • Browse all Engineering functions at /categories/engineering/ for related formulas.
  • IMLN syntax: =IMLN(inumber)
  • inumber (required): Complex number
  • Confirm IMLN arguments match the syntax shown above before filling down.
  • Lock table and range references with $ when copying formulas across rows or sheets.

Formula checklist before you copy down

  • Confirm IMLN arguments match the syntax shown above before filling down.
  • Lock table and range references with $ when copying formulas across rows or sheets.
  • If results look wrong, check for text stored as numbers and invisible spaces with TRIM.
  • Spot-check three known input rows manually against expected output.

Related Excel functions

  • IMEXP (/functions/imexp/): Returns the exponential of a complex number.
  • IMLOG10 (/functions/imlog10/): Returns the base-10 logarithm of a complex number.
  • LN (/functions/ln/): Returns the natural logarithm (base e) of a number.

Errors to watch for

  • #NUM! if not valid complex number — review causes on linked error pages in the directory.

Copy-paste audit workflow

  • Enter IMLN on three test rows with known expected output documented on a QA tab.
  • Fill down only after absolute references are locked on lookup tables and rate tables.
  • Compare against manual calculation or a calculator for financial and statistical functions.
  • Search this directory for comparison guides when choosing between similar functions in the same category.

IMLN worked examples to copy

  • =IMLN("1+i") — Natural log of complex. Expected result: 0.347+0.785i.

IMLN reference summary for crawlers and offline review

  • IMLN belongs to the Engineering category in Excel. Returns the natural logarithm of a complex number.
  • Full syntax: =IMLN(inumber). Open /functions/imln/ for parameters, FAQs, and related pages.
  • Common mistakes: #NUM! if not valid complex number
  • Pair this function with comparison guides when another Excel formula might fit the same task better.
  • Review fix-excel-formula-errors when unexpected errors appear after upgrading Excel or sharing across locales.