Category Archives: Maths

Evaluate integrals to a specified tolerance

Posted on 10/03/2009 by dougaj4

A previous post presented a user defined function (UDF) to perform a numerical integration of a function specified as a text string.  The UDF allowed the number of subdivisions of the integration range to be specified, but the number of subdivisions required to … Continue reading →

Posted in Excel, Maths, Newton, UDFs | Tagged , , , , , | 2 Comments

IP.xls updated

Posted on 16/02/2009 by dougaj4

The spreadsheet IP.xls has been updated (previous post) with the addition of a function to find the minimum perpendicular distance from a point (or series of points) to a polyline: Pdist =PDist(Line,Points) Line is a range with at least two rows containing … Continue reading →

Posted in Coordinate Geometry, Excel, Maths, Newton, UDFs, VBA | 1 Comment

Significant Figures

Posted on 28/12/2008 by dougaj4

Excel does not provide any built in functions to round values to a specified number of significant figures.  The UDF below, recently posted at the Eng-Tips forum, will do the job: Public Function sigfig(my_num, digits) As Double Dim num_places As Integer … Continue reading →

Posted in Excel, Maths, UDFs, VBA | Tagged , , | 5 Comments

Solving simultaneous equations – Fortran dll

Posted on 20/12/2008 by dougaj4

The file simultaneous.zip has been modified to allow access to a Fortran simultaneous equation routine, compiled as a dll.  The original file was posted in solving simultaneous equations.  The advantages of a compiled routine include: Much better performance Greater precision through … Continue reading →

Posted in Arrays, Fortran, Link to dll, Maths, UDFs, VBA | Tagged , , , , , | 3 Comments

Trigonometric Functions – dll

Posted on 11/12/2008 by dougaj4

I have converted the trigonometric functions presented in this earlier post into a Fortran dll.  The dll and associated spreadsheet and add-in files can be downloaded from here. This file and the associated file Trig.dll provide trigonometric and hyperbolic functions not … Continue reading →

Posted in Excel, Link to dll, Maths, Newton, UDFs | Tagged , , , , , , | 2 Comments