Category Archives: Coordinate Geometry

Cubic Spline Update

Posted on 16/12/2009 by dougaj4

The previous post in this series presented a User Defined Function (UDF) to fit  a cubic spline to a series of points defined by XY coordinates.  Each segment of the resulting spline is defined by a separate cubic curve, which may be … Continue reading →

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

Geometric Tools

Posted on 30/09/2009 by dougaj4

I was recently sent a link to: Geometric Tools Documentation Which has a host of pdf files with detailed instructions on all manner of geometric calculations.  The focus of the site is animation for games programs, but there is plenty … Continue reading →

Posted in Coordinate Geometry, Maths, Newton | Tagged , | Leave a comment

Finding Circle Centres in 3D

Posted on 18/08/2009 by dougaj4

In 2 new functions for IP.xls I described two Excel User Defined Functions (UDFs) to find the radius and centre of a circle defined by 3D coordinates for either 3 points on the circumference, or for two tangent points and the … Continue reading →

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

Intersections, interpolations, and rotations

Posted on 10/08/2008 by dougaj4

Amongst the many and varied functions provided by Excel (or as far as I know any other spreadsheet) there are none that provide a one step process for linear interpolation, finding the intersection points of lines, or conversion between polar … Continue reading →

Posted in Coordinate Geometry, Excel, UDFs, VBA | Tagged , , , , , , | 37 Comments