How to create membership functions matlab in triangular form?

Hi, hoping somone can help

i add the rule 1 and 2 with trimf function but how can i plot the rule 3 and 4 pleas (see the attched images) thanks )

Answer 1

[darova]

Use sine wave

x = 0:pi/2:20;
y = sin(x);
plot(x,y)

[mindo akami]

Hi, thanks for your answer darova

but if we take the image closely the rule 3 for example is like this and i don't know how to do it

[darova]

Maybe manual solution?

x = [-180 -90 -90 90 90 180];
y = abs(sind(x));
y(3:4) = 0;
plot(x,y)

Answer 2

[Sam Chak]

Hi @mindo akami

You probably have already learned the manual way to plot these. Since this is unanswered and if you are still interested in learning to plot the 'fuzzy way', here is the code:

x = -180:0.1:180;       % set the domain of discourse

y1 = trimf(x,[-90 0 90]);                               % Rule 1
y2 = 1 - y1;                                            % Rule 2
y3 = trimf(x,[-180 -90 -90])  + trimf(x,[90 90 180]);	% Rule 3
y4 = trimf(x,[-180 -180 -90]) + trimf(x,[90 180 180]);	% Rule 4

h = plot(x, y1, 'r-', x, y2, 'g-', x, y3, 'b-', x, y4, 'm-');
set(h, 'LineWidth', 1.5)
xticks([-180 -90 0 90 180]);
xlabel('x_{1}, (degree)');
ylabel('Degree of Membership, \mu');

The line colors follow the original image that you posted here:

https://www.mathworks.com/matlabcentral/answers/853935-how-to-design-the-membership-function-in-matlab

Result: