Category Archives: UDFs

Evaluating Pi …

Posted on 12/04/2009 by dougaj4

… to 15 decimal places in one easy step (or not too difficult step). In my previous post one of the examples given of the use of the Gaussian Quadrature function was to evaluate the value of Pi.  Let’s look at … Continue reading →

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , | 4 Comments

Gaussian Quadrature

Posted on 10/04/2009 by dougaj4

The previous post on integration provided an Excel User Defined Function (UDF) to perform numerical integration using Simpson’s Rule or the Trapezoidal Rule.  A third method is Gaussian Quadrature which is often much more accurate and/or quicker than Simpson’s Rule.  The UDF GaussInt() … Continue reading →

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 27 Comments

Another update to IP.xls

Posted on 07/04/2009 by dougaj4

Following some suggestions from Mike Seymour I have modified my polyline intersection function, and added a new version. The changes are: The data ranges for the new function, IP4(), are entered as four separate ranges, so the X and Y … Continue reading →

Posted in Excel, Maths, UDFs, VBA | Tagged , , , , | 1 Comment

A Sort Function

Posted on 23/03/2009 by dougaj4

There is often a need to sort data within a VBA routine, but VBA does not have a built in sort function, so I recently had a look for what is on offer on the Internet. Chip Pearson has an … Continue reading →

Posted in Arrays, Excel, UDFs, VBA | Tagged , , , | 21 Comments

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