IMCOS Function

Excel Functions › Engineering

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The Excel IMCOS function returns the cosine of a complex number — part of Excel’s complex-number toolkit for engineering and signal analysis.

Quick answer:
=IMCOS("3+4i") // complex cosine

Syntax

=IMCOS(inumber)
ArgumentDescription
inumberRequiredA complex number.

How to use it

IMCOS returns the cosine of a complex number. Complex numbers are written as text like "3+4i" (or with a "j" suffix). Build them with COMPLEX and pull the parts back out with IMREAL and IMAGINARY.

=IMCOS("3+4i") // complex cosine

All IM functions take and return text. Keep complex numbers as text strings throughout your calculation chain; use IMREAL / IMAGINARY only when you need numeric parts for charts or further math.

Try it: interactive demo

Live demo

Enter a complex number (a+bi) and see the formula IMCOS would evaluate.

Practice workbook

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Download the free IMCOS practice workbook
Every example on this page, ready to open in Excel — plus practice challenges with answers on a separate tab. No sign-up required.

Frequently asked questions

How are complex numbers stored in Excel?
As text strings like "3+4i" or "3+4j". Build them with COMPLEX and read parts with IMREAL/IMAGINARY.
Does IMCOS return text or a number?
Text — a complex number string you can feed into other IM functions.
Can I mix i and j suffixes?
No — all complex numbers in one calculation must use the same suffix. COMPLEX lets you choose which.
What if my real or imaginary part is zero?
Excel simplifies the display: COMPLEX(3,0) returns "3" and COMPLEX(0,4) returns "4i".

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Related functions: COMPLEX · IMREAL · IMAGINARY · IMABS · IMSUM