Kardi Teknomo's Blog

Revision to LDA numerical example

Teknomo — Tue, 15 Dec 2009 02:54:17 +0000

There was typing mistake in calculating the pool within group covariance matrix.

It was writen as 3/7*0.1349+4/7*2.142=1.689 while the correct one should be 4/7*1.349+3/7*2.142=1.689

Thanks for Gal and Dafna Hirschfeld for pointing this out.

See the updated version in : http://people.revoledu.com/kardi/tutorial/LDA/Numerical%20Example.html

Spanish Translation of Numerical Example for K means

Teknomo — Tue, 01 Dec 2009 02:40:25 +0000

Spanish Translation of Numerical Example for K means tutorial is available. Thanks to Jaime Orjuela (Escuela Colombiana de Ingeniería) from Columbia.

See: http://people.revoledu.com/kardi/tutorial/kMean/EjemploNumerico.htm

Data Table in MS Excel

Teknomo — Sun, 01 Nov 2009 03:08:03 +0000

Sometimes, you would like to create a table from a series of complicated formulas. In that case, you need Data Table.

A new tutorial on how to use Data table (What if Analysis) in Excel using simple example how to create data table with one input variable and two input variables is available in http://people.revoledu.com/kardi/tutorial/What-If-Analysis/index.html

Footrule distance for non-unique rank

Teknomo — Sat, 05 Sep 2009 04:59:42 +0000

I have updated footrule distance tutorial with additional example of non-unique rank. Often we encounter rank that repeating such as 1, 2, 3, 3, 4 instead of 1,2,3,4,5. How to compute footrule distance for such non-unique rank?

Please visit

http://people.revoledu.com/kardi/tutorial/Similarity/FootruleDistance.html for the answer.

Update Distance Matrix of K-Means Clustering Tutorial

Teknomo — Wed, 29 Jul 2009 23:46:42 +0000

Code for distance matrix computation is updated. Now it can handle multidimensional variables. The previous code that work only for 2 dimensions is given here for historical purposes. function d=dist(A,B) % DIST return distance matrix between point A=[x1 y1] and B=[x2 y2] % Number of points in A and B are not necessarily the same. % It can be use [...]

Finding Eigen Value using Microsoft Excel Tutorials

Teknomo — Tue, 28 Jul 2009 16:29:55 +0000

Here is frequently asked question from web visitors: Thanks first of all for putting up this great site! I have a question regarding calculation of eigen values for a 3×3 matrix. While I could easily calculate eigen values and vectors for a 2×2 matrix (because after you get one value, ou can simply subtract it from the [...]