Summary

The Excel IMSIN function returns the sine of a complex number.

Purpose 

Get sine of complex number.

Return value 

Returns the sine of the complex number.

Syntax

=IMSIN(complex_num)
  • complex_num - The complex number in the form "x+yi".

How to use 

The Excel IMSIN function returns the sine of a complex number. For instance, given "1+1i" as input, the function returns the complex number equal to the sine of the input.

=IMSIN("1+1i") // returns 1.29845758141598+0.634963914784736i

Given real number input, the function behaves like the sine function. For example, given π + 0i as input the function returns 3.23108914886517E-15 (approximately zero). The sine of π is zero, but due to floating-point precision, it returns a very small number close to zero.

=IMSIN(COMPLEX(PI(),0)) // returns 3.23108914886517E-15

Explanation

Mathematically, the sine of a complex number can be represented using a combination of the standard and hyperbolic trigonometric functions.

Definition of sine for a complex number.

If B6 contains a complex number in the form "x+yi", this is equivalent to the following formula.

=COMPLEX(
    SIN(IMREAL(B6))*COSH(IMAGINARY(B6)),
    COS(IMREAL(B6))*SINH(IMAGINARY(B6))
)

Alternatively, the sine of a complex number can be defined in terms of the exponential function, where "z=x+yi".

Sine of a complex number in terms of the exponential function.

If B6 contains a complex number in the form "x+yi", this is equivalent to the following formula.

=IMDIV(
    IMSUB(
        IMEXP(IMPRODUCT(COMPLEX(0,1), B6)), 
        IMEXP(IMPRODUCT(COMPLEX(0,-1), B6))
    ),
    COMPLEX(0, 2)
)

 

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.