Plot functions in MATLAB

Question

hasan s 2021-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/895362-plot-functions-in-matlab

评论： Les Beckham 2021-8-15

graph.m

Hello every one,

If possible..I need to draw these five functions (in the picture) at the same time so that the output is one drawing containing the drawing of all these five functions with one different color for each function..please, is this possible in MATLAB?

And put the square of the indicative color for each function on the output drawing.

This is my attempt, but I got an error while executing

If any Prof. can help me...thanks alots

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Answer 1

Les Beckham 2021-8-10

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Since I don't have the Statistics and Machine Learning Toolbox (for the unifrnd() function), I used the base Matlab function rand() instead.

% v1=unifrnd(0,1,1,m);

% l1=unifrnd(0,1,1,m);

% u1=unifrnd(1,2,1,m);

v1 = rand(1,m);

l1 = rand(1,m);

u1 = rand(1,m)*2;

That is the only change I made and the script generated a plot.

When you post a question to Matlab Answers, I would suggest showing the exact error message that you are seeing, or explaining how your result differs from what you expect. Please show your error message (all of the red text that comes up in the command window).

Your code is generating 100 different lines in the plot (since G is 100x101) rather than the 5 that you suggest that you expect.

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hasan s 2021-8-11

编辑：hasan s 2021-8-11

plot2.m

thanks alot prof.

I could not write the code in the right form, the functions g1 , and g2, and g3,and g4,and g5 ,did not appear clearly ,,,I could not distinguish g1 , and g2, and g3,and g4,and g5

I mean , I want to plot g1 (with all lines)in one color, then plot g2 (with all lines)in another color ,...to g5(with all lines) in a different color , the output colour are 5 color only ,

...such as

1- the first color for g1 which is

part0 = 0 .* ( x >= b);

part1 = (5-x)./(b-a) .* (x >= a & x <= b);

part2 = 2 .* ( x <= a);

g1 = part0 + part1 + part2;

plot(x, g1);;ylim([color 1, as red])

2- the second color for g2 which is

part3 = 0 .* (x<=a);

part4= (x-4)./(b-a) .* (x >= a & x <= b);

part5 = (6-x)./(c-b) .* (x >= b & x <= c);

part6 = 0 .* (x >= c);

g2 = part3 + part4 + part5 + part6;

plot(x, g2);;ylim([color 2, as blue])

2- the third color for g3 which is

part7 = 0 .* (x<=b);

part8= (x-5)./(b) .* (x >= b & x <= c);

part9= 2 .* (x >= c & x <= d);

part10= (8-x)./(e-d) .* (x >= d & x <= e);

part11= 0 .* (x >= e);

g3 = part7+ part8+ part9+part10+part11;

plot(x, g3);;ylim([color 3, as green])

4- the 4 color for g4 which is

part12 = 0 .* (x<=d);

part13= (x-7)./(e-d) .* (x >= d & x <= e);

part14= (9-x)./(6) .* (x >= e & x <= f);

part15= 0 .* (x >= f);

g4 = part12+part13+part14+part15;

plot(x, g4), ;ylim([color 4, as Orange])

5- the 5 color for g5 which is

part16 = 0 .* ( x <= e);

part17 = (x-8)./(15) .* (x >= e & x <= f);

part18 = 2 .* (x >= f );

g5 = part16+part17+part18;

plot(x, g5);ylim([color 5 as yellow])

....................

the square of the indicative color in the output for g1, g2,g3,g4,g5

...........................

This is another attempt, can you modify it or give me the appropriate code?thanks alot

Les Beckham 2021-8-14

在 MATLAB Online 中打开

I adapted your second attempt and now we are getting 500 lines on the plot. Again, because your g1-g5 variables have dimensions 100x101. Since I don't understand your math or what you are attempting to model here, I don't know what to suggest.

Here is the updated code. I used cyan for g4 instead of orange as it is easier to specify with the "short name" form of a color specifier.

format long
m=100;
% v1=unifrnd(0,1,1,m);
% l1=unifrnd(0,1,1,m);
% u1=unifrnd(1,2,1,m);
v1 = rand(1,m);
l1 = rand(1,m);
u1 = rand(1,m)*2;
a = 0.1*l1';
b = 2*v1';
c = 3*v1';
d = 4*u1';
e=5*v1';
f=6*u1';
x = 0:0.1:10;
%% Attempt #2
% 1- the first color for g1 which is 
part0 = 0 .* ( x >= b);
part1 = (5-x)./(b-a) .* (x >= a & x <= b);
part2 = 2 .* ( x <= a);
g1 = part0 + part1 + part2;
% plot(x, g1);;ylim([color 1, as red])
% 2- the second color for g2 which is
part3 = 0 .* (x<=a);
part4= (x-4)./(b-a) .* (x >= a & x <= b);
part5 = (6-x)./(c-b) .* (x >= b & x <= c);
part6 = 0 .* (x >= c);
g2 =  part3 + part4 + part5 + part6;
% plot(x, g2);;ylim([color 2, as blue]) 
% 3- the third color for g3 which is 
part7 = 0 .* (x<=b);
part8= (x-5)./(b) .* (x >= b & x <= c);
part9= 2 .* (x >= c & x <= d);
part10= (8-x)./(e-d) .* (x >= d & x <= e);
part11= 0 .* (x >= e);
g3 =  part7+ part8+ part9+part10+part11;
% plot(x, g3);;ylim([color 3, as green]) 
% 4- the 4 color for g4 which is 
part12 = 0 .* (x<=d);
part13= (x-7)./(e-d) .* (x >= d & x <= e);
part14= (9-x)./(6) .* (x >= e & x <= f);
part15= 0 .* (x >= f);
g4 = part12+part13+part14+part15;
% plot(x, g4), ;ylim([color 4, as Orange]) 
% 5- the 5 color for g5 which is 
part16 = 0 .* ( x <= e);
part17 = (x-8)./(15) .* (x >= e & x <= f);
part18 = 2 .* (x >= f );
g5 = part16+part17+part18;
% plot(x, g5);ylim([color 5 as yellow]) 
plot(x, g1, 'r-s', x, g2, 'b-s', x, g3, 'g-s', x, g4, 'c-s', x, g5, 'y-s')