Plot Piecewise function graph

Question

L 2024-3-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2092486-plot-piecewise-function-graph

评论： Alexander 2024-3-10

在 MATLAB Online 中打开

Here's my code but i can't get the graph as shown in the picture.

% Use conditional statements and loops to calculate function values for

% different input ranges

x = -2.99*pi: 0.01: 3*pi; % Create domain from -2.99pi to 3pi, at increment of 0.01

y = zeros(1,length(x));

for i = 1: length(x) % For each statement i, it will pass through each value of x

if x(i) > -3*pi && x(i) < -pi % If x lies at −3pi < x <-pi,

y(i) = 1./log(2)*sin(x(i)); % the function is y = 1/(ln2)(sinx)

elseif x(i) >= -pi && x(i) <=2 % If x lies at -pi <= x <= 2,

y(i) = abs(x(i)) - 3; % the function is y = |x| -3

else

y(i) = exp(1); % If x doesn't lies at above interval, the function is y = e

end

plot(x, y);

text(3.2\pi, 0.2 , 'x'); text(0.2\pi, 3.5, 'y');

axis([-4\pi 4\pi -4 4]);

xticklabels({'-3\pi', '-2\pi', '-\pi', '0', '\pi', '2\pi', '3\pi'}); % Display tick marks along the x-axis by specifying the text to show pi symbol

yticks(-3: 1: 3); % Display tick marks along the y-axis 0.5,1 and 1.5

box off;

**This is the graph should be look like.

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L 2024-3-10

编辑：L 2024-3-10

How to create asymptotes?

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Answer 1

Paul 2024-3-9

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2092486-plot-piecewise-function-graph#answer_1423116

在 MATLAB Online 中打开

This line

y(i) = 1./log(2)*sin(x(i));

is incorrect.

The order of operations for multiplication and division is that they are evaluated in order from left to right. So that line could also be expressed as

y(i) = ( 1./log(2) ) * sin(x(i));

i.e., the division is done first, and the result of the division becomes the first operand for the multiplication.

Hopefully that gives you a clue as to how to fix the code (at least that part of it).

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Paul 2024-3-10

Yes, those two lines do yield the same result. The first line is used in the code in the question. I used the extra parentheses in the second to emphasize the order of operations used to evaluate the first.

Neither of those lines are a correct implementation of

which was the point I was trying to make to lead the OP to the correct Matlab expression. I think the OP did eventually get the correct expression, but that comment has since been deleted.

Alexander 2024-3-10