Études for Erlang

Étude 3-1: Pattern Matching

Use atoms and pattern matching to make your area function calculate the area of a rectangle, triangle, or ellipse. If your parameters are Shape, A and B, the area for the atom rectangle is A * B, where A and B represent the length and width. For a triangle atom, the area is A * B / 2.0, with A and B representing the base and height of the triangle. For an ellipse atom, the area is math:pi() * A * B, where A and B represent the major and minor radiuses.

Here is some sample output.

1> c(geom).
{ok,geom}
2> geom:area(rectangle, 3, 4).
12
3> geom:area(triangle, 3, 5).
7.5
4> geom:area(ellipse, 2, 4).
25.132741228718345

See a suggested solution in Appendix A.