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Visual Basic Function to Format Complex Numbers

This article was previously published under Q151338
This article has been archived. It is offered "as is" and will no longer be updated.
Because Microsoft Excel stores complex numbers as text, complex numberscannot be formatted like real numbers. This article provides sample codefor a user-defined function that applies number formats to complex numbers.
More information
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. Complex numbers are real and imaginary coefficients which combine to form acomplex number. They are in the form of x+yi or x+yj where x is the realcoefficient and y is the imaginary coefficient. Complex numbers alwayscarry a suffix of the letter i or j.

The function in this article takes three arguments: the number to beformatted, a format code for the real component, and a format code for theimaginary component. For example, the function
would display the complex number in cell A1 with two decimal places for thereal component and four decimal places for the imaginary component.

You can also use multisection formats to format positive, negative, andzero components differently. For example, the function
would have the same result as the earlier example, but with zero componentsdisplaying as "0" rather than including extra zeroes to the right of thedecimal point. If you use a multisection format, the formats for negativenumbers must begin with a "-" (minus sign) as in the example.

Sample Visual Basic Procedure

   Option Explicit   Function FormatComplex(NumToFormat As String, RealFormatCode As _       String, ImagFormatCode As String)       Dim PlusOrMinus As String       Dim CharPosition As Integer       ' Is NumToFormat real?       If Right(NumToFormat, 1) <> "i" Then           ' NumToFormat is real.           FormatComplex = Format(NumToFormat, RealFormatCode)       Else           ' NumToFormat is either imaginary or complex.           ' Search NumToFormat from right until + or - or left end is           ' reached.           PlusOrMinus = "not found"           For CharPosition = Len(NumToFormat) - 1 To 1 Step -1               PlusOrMinus = Mid(NumToFormat, CharPosition, 1)               If PlusOrMinus = "+" Or PlusOrMinus = "-" Then Exit For           Next           ' Is NumToFormat complex or imaginary?           If (PlusOrMinus = "+" Or PlusOrMinus = "-") And _               CharPosition <> 1 Then               ' NumToFormat is complex.               ' Is imaginary component negative?               If Mid(NumToFormat, CharPosition, _                   Len(NumToFormat) - CharPosition) < 0 Then                   ' Imaginary component is negative, so "-" does not need                   ' to be added.                   FormatComplex = Format(Left(NumToFormat, _                       CharPosition - 1), RealFormatCode) & _                       Format(Mid(NumToFormat, CharPosition, _                       Len(NumToFormat) - CharPosition), _                       ImagFormatCode) & "i"               Else                   ' Imaginary component is not negative, so "+" needs to                   ' be added.                   FormatComplex = Format(Left(NumToFormat, _                       CharPosition - 1), RealFormatCode) & "+" & _                       Format(Mid(NumToFormat, CharPosition, _                       Len(NumToFormat) - CharPosition), _                       ImagFormatCode) & "i"               End If           Else               ' NumToFormat is imaginary.               FormatComplex = Format(Left(NumToFormat, _                   Len(NumToFormat) - 1), ImagFormatCode) & "i"           End If       End If   End Function				
For additional information about getting help with Visual Basic for Applications, click the article number below to view the article in the Microsoft Knowledge Base:
226118 OFF2000: Programming Resources for Visual Basic for Applications
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Article ID: 151338 - Last Review: 11/01/2013 22:52:00 - Revision: 3.0

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