Electronic Proceedings of the Eighth Annual International Conference on Technology in Collegiate Mathematics

Houston, Texas, November 16-19, 1995

Paper C091

Modeling with the TI-85

Neil Eklund

Centre College
600 W. Walnut
Danville, KY 40422-1394
Phone: (606) 238-5405
Fax: (606) 236-9610

list of all papers by this author

Click to access this paper: paper.pdf


If the overdetermined system of equations is written in the form Xa = y where a is the vector of unknown coefficients, the normal equations for a are (XTX)a = XTy. Under appropriate conditions XTX is invertible as well as symmetric and, hence, a = (XTX)-1XTy. The least squares error is shown to be E = yT{I - X(XTX)-1XT}y. This modeling technique will be applied to non-linear data.

Mathematical Notation:

Keyword(s): modeling, TI-85, linear algebra