# The Excel IMLOG10 Function

Related Function:
IMLN Function
Common Logarithm of a Complex Number

The common (base 10) logarithm of a complex number is calculated by the equation:

## Basic Description

The Excel Imlog10 function returns the common (base 10) logarithm of a supplied complex number.

The format of the function is:

IMLOG10( inumber )

where the inumber argument is a complex number.

Note that complex numbers are simply stored as text in Excel. When a text string in the format "a+bi" or "a+bj" is supplied to one of Excel's built-in complex number functions, this is interpreted as a complex number.

Also the complex number functions can accept a simple numeric value, as this is equivalent to a complex number whose imaginary coefficient is equal to 0.

Therefore, the inumber argument can be supplied to the Excel Imlog10 function as either:

• A simple number
or
• A complex number encased in quotation marks - eg. "5+3i"
or
• A reference to a cell containing a complex number or a numeric value
or
• A value returned from another Excel function or formula

These are all included in the examples below.

## Imlog10 Function Examples

The spreadsheet below shows 4 different examples of the Imlog10 function.

Formulas:
AB
1 =IMLOG10( 2 )
2 =IMLOG10( "1-2i" )
32.5-i=IMLOG10( A3 )
4 =IMLOG10( COMPLEX( 1, -1 ) )
Results:
AB
1 0.301029995663981
2 0.349485002168009-0.480828578784234i
32-i0.349485002168009-0.201359598136687i
4 0.150514997831991-0.34109408846046i

Note that, in cell B1 of the above spreadsheet, the supplied inumber argument is the integer 2, which is equal to the complex number 2+0i.

Further information and examples of the Excel Imlog10 function can be found on the Microsoft Office website

## Imlog10 Function Errors

If you get an error from the Excel Imlog10 Function, this is likely to be one of the following:

Common Errors
 #NUM! - Occurs if the supplied inumber argument is not recognised as a complex number. #NAME? - Occurs when Analysis ToolPak add-in is not enabled in your Excel.You will need to enable the add-in if you want to use the Excel complex number functions.