Category Archives: Maths

When does 35 not equal 35?

Posted on 20/12/2011 by dougaj4

… and when does 35 – 35 not equal zero? In the first case the answer is when one “35” is on an Excel spreadsheet and the other 35 is in VBA.  The question arose from the ongoing continuous beam … Continue reading →

Posted in Excel, Maths, Newton, VBA | Tagged , , , | 12 Comments

Linest, NPV, IRR and solving polynomials

Posted on 01/12/2011 by dougaj4

In a comment on Using LINEST for non-linear curve fitting Lori Miller posted a formula that found the coefficients fitting a cubic polynomial curve to a set of data, then solved the resulting equation to find the X value for a given … Continue reading →

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 3 Comments

Spline Interpolation Alternatives

Posted on 04/09/2011 by dougaj4

A recent post at Jon Peltier’s Blog looks at an “on-sheet” method of performing linear interpolation on a set of tabular data, and the following comments include a number of alternative ways of carrying out the same process, and also some … Continue reading →

Posted in Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , | 7 Comments

Area from Vectors

Posted on 27/08/2011 by dougaj4

The previous post looked at User Defined Functions (UDFs) for working with vectors, including examples of functions to find the area of polygons defined by coordinates.  In this post the functions will be extended to find other section properties (such … Continue reading →

Posted in Arrays, Coordinate Geometry, Excel, Maths, UDFs, VBA | Tagged , , , , , , | 5 Comments

Dots and Crosses

Posted on 21/08/2011 by dougaj4

The comments from Bill Harvey in the previous post prompted me to have a closer look at the functions available in Excel for working with vectors.  Here is a complete list of them: =SUMPRODUCT() (Equivalent to the vector dot product) This … Continue reading →

Posted in Arrays, Coordinate Geometry, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , | 11 Comments