Category Archives: Maths

Global to Local for plates (and three node beams)

Posted on 02/03/2014 by dougaj4

The Glob_to_Loc function (see Converting from global to local coordinates (and vice versa) ) converts forces and deflections of a beam from the global coordinate system to the local system, defined by the longitudinal axis of the beam and a rotation angle … Continue reading →

Posted in Coordinate Geometry, Excel, Finite Element Analysis, Frame Analysis, Link to Python, Maths, Newton, Strand7, UDFs, VBA | Tagged , , , , , , , | 3 Comments

The angle between two vectors, Python version

Posted on 01/03/2014 by dougaj4

I posted a VBA function to return The angle between two vectors, in 2D or 3D last year, and have just discovered that Python and Numpy are lacking this function.  Since all the suggested code I found in a quick search used: Cos θ … Continue reading →

Posted in Coordinate Geometry, Excel, Link to Python, Maths, Newton, NumPy and SciPy | Tagged , , , | 10 Comments

Rabbits, Foxes, and Lorenz Attractors

Posted on 23/02/2014 by dougaj4

Following comments here and here I have added two examples to the ODE Solver spreadsheet showing use of the ODE function to solve systems of differential equations with two or more coupled equations. The new version (including full open source … Continue reading →

Posted in AlgLib, Differential Equations, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , , , , | 2 Comments

Cubic splines with horizontal data

Posted on 16/02/2014 by dougaj4

Following a request here I have modified my cubic spline functions to accept input arranged  in rows as well as columns.  By default the output arrays will have the same orientation as the range of interpolation X values, but I have also added … Continue reading →

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

Two MaxAbs functions

Posted on 20/01/2014 by dougaj4

Excel does not have a built-in function to find the maximum absolute value of a range, perhaps because the Max() and Abs() functions can be combined in an array function: =Max(Abs(datarange)) This solution has a number of drawbacks however: The … Continue reading →

Posted in Arrays, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , | 9 Comments