Category Archives: Arrays

Finding Prime Numbers with Excel, and using Array Formulas

Posted on 18/11/2008 by dougaj4

Download Primes.zip. Several of the puzzles at Project Euler (see previous post) require the finding of prime numbers, for instance what is the 10,001th prime number?  Searching the Web for some ready made solutions I found this array formula at … Continue reading →

Posted in Arrays, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , | 28 Comments

Linking Excel to C – 3; Avoiding bottlenecks

Posted on 08/09/2008 by dougaj4

The previous post in this series included a C dll to solve cubic polynomial equations that could be called from VBA.  The performance of this routine is compared with a VBA routine using a similar algorithm in the sceenshot below (rows … Continue reading →

Posted in Arrays, Excel, Link to dll, UDFs, VBA | Tagged , , , | 2 Comments

Solving simultaneous equations

Posted on 27/08/2008 by dougaj4

Solving a series of simultaneous equations is a task frequently required in engineering and scientific analysis.  Excel provides the tools to perform this task quickly and easily, but the procedure is not documented in the on-line help (so far as … Continue reading →

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

Section Properties UDF and UDF charting

Posted on 14/03/2008 by dougaj4

The technique for calculating section properties from coordinates is conveniently coded into a UDF: Function Area(xy_range As Variant) As Double Dim XYcells As Variant Dim N As Long, NumX As Long Dim XD As Double, YSum As Double XYcells = … Continue reading →

Posted in Arrays, Charts, Excel, UDFs | Tagged | 6 Comments

Ranges and Arrays – 2

Posted on 05/03/2008 by dougaj4

Yesterday we looked at how to get data from a worksheet range into a VBA array.  Today’s post looks at the opposite operation; writing an array to a worksheet range.  With a UDF it couldn’t be simpler: Function MyFunction() as … Continue reading →

Posted in Arrays, Excel, UDFs | 1 Comment