polimd/SC_lab_1.md

9 November 2015

Soft Computing - Matlab lesson

Lake level problem

The level of the water nees to be periodically rised and lowered to kill mosquito eggs.

Measuring the height of the water

Done by measuring the level against a wall,

The level can vary in a range of -2, +2 meters, [m]

Membership functions

We have to decide:

• The minimum value
• The maximum value
• The shape of the function.

Our three labels will be

• below
• ze(ro)
• above

For the below membership function we choose a trapezoid function

For the zero MF we choose a triangular function

For the above MF we choose a trapezoid function

The two trapezoid functions have zero value in the center of the zero function.

Output functions

singletons aren't provided by matlab, instead we need to create a very narrow triangle.

The output function is determined by 5 sigletons at each laber:

• zero
• few
• half
• lot
• full

Rules

We have to add rules as following:

Height	Request	Output
below	zero	zero
below	half	few
below	max	few
below	few	few
below	lot	few
zero	zero	zero
zero	half	half
zero	max	max
zero	few	few
zero	lot	lot
zero	zero	few
zero	half	lot
zero	max	max
zero	few	half
zero	lot	max

Adding information

If we have weather forecast available as another input
We can add another membership function.

Additional Rules

Rain	Output
Zero	Few
Few	Few
Half	Half
A-Lot	A-Lot
Max	Max