Engineering

IMCOS Function in Excel

Returns the cosine of a complex number.

Syntax

  • =IMCOS(inumber)

Arguments

  • inumber (required): Complex number

Examples

  • =IMCOS("1+i") - Cosine of complex number - Result: 0.833-0.988i

IMCOS 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
  • Signal processing

Frequently asked questions

  • What is the IMCOS function in Excel? IMCOS returns the cosine of a complex number. The syntax is =IMCOS(inumber). Typical use cases include complex analysis, engineering, signal processing.
  • How do I use the IMCOS function? To use IMCOS, type =IMCOS( 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 IMCOS not working in my Excel? Common issues with IMCOS include #NUM! if not valid complex number. Start by checking the syntax =IMCOS(inumber), then verify each referenced cell or range.

Editorial review

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

When to use IMCOS

  • Complex analysis — common Engineering scenario for IMCOS.
  • Engineering — common Engineering scenario for IMCOS.
  • Signal processing — common Engineering scenario for IMCOS.

IMCOS in the Engineering category

  • Browse all Engineering functions at /categories/engineering/ for related formulas.
  • IMCOS syntax: =IMCOS(inumber)
  • inumber (required): Complex number
  • Confirm IMCOS 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 IMCOS 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

  • IMSIN (/functions/imsin/): Returns the sine of a complex number.
  • COMPLEX (/functions/complex/): Converts real and imaginary coefficients into a complex number.
  • COS (/functions/cos/): Returns the cosine of an angle specified in radians.

Errors to watch for

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

Copy-paste audit workflow

  • Enter IMCOS 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.

IMCOS worked examples to copy

  • =IMCOS("1+i") — Cosine of complex number. Expected result: 0.833-0.988i.

IMCOS reference summary for crawlers and offline review

  • IMCOS belongs to the Engineering category in Excel. Returns the cosine of a complex number.
  • Full syntax: =IMCOS(inumber). Open /functions/imcos/ 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.