1Daniel Baur / Numerical Methods for Chemical Engineerse

Programming Tips:While Loops and Comparisons

Daniel Baur

ETH Zurich, Institut für Chemie- und Bioingenieurwissenschaften

ETH Hönggerberg / HCI F128 – Zürich

E-Mail: daniel.baur@chem.ethz.ch

http://www.morbidelli-group.ethz.ch/education/index

2Daniel Baur / Numerical Methods for Chemical Engineerse

While Loops with limited Iterations

In order to keep a while loop from iterating forever, use one of the following two schemes:

3Daniel Baur / Numerical Methods for Chemical Engineerse

Comparing Entire Vectors and Matrices The easiest way to compare two vectors or matrices is to

do it directly:

4Daniel Baur / Numerical Methods for Chemical Engineerse

Addendum: Implicit Trapezoid Method

If the Jacobian matrix is constant, there is no need to solve linear systems in the iteration equations:

Where A can be calculated once using A = (I – h/2*J) \ (I + h/2*J);

1

1

1

1

2 2

2 2

n n

n n

n n

h hy y

h hy y

y y

I J I J

I J I J

A