Problems using Plot function

Question

SIDDHARTHA SIDDHARTHA 2023-6-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1978354-problems-using-plot-function

评论： SIDDHARTHA SIDDHARTHA 2023-6-5

采纳的回答： Walter Roberson

Hi,

I am trying to use the plot function, however, there is no line visible on the graph. lets say, I have

A=[1.1,1.2,1.3];

B=[2.1,2.2,2.3];

C=[3.1,3.2,3.3];

What I want is a plot of [1:3:1] on the X axis and values A(1),B(1),C(1) plotted with respect to point 1, A(2),..C(2) with respect to 2 and A(3)..C(3) with respect to point 3 on X axis.

I thought I would first declare a 3X3 zero matrix and subsequently save all the values of A B C in this array, and try to plot it. No matter what I am doing, I am getting a null plot.

A=[1:3];

B=[4:6];

C=[5:3];

for i=1:3

f(i)=A(i)^2;d(i)=5*B(i);v(i)=A(i)+B(i);

plot (i,f(i),d(i),v(i))

hold on

end

can anyone please help? Thanks in advance

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Answer 1

Walter Roberson 2023-6-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1978354-problems-using-plot-function#answer_1250439

You are plotting one point at a time. By default, plot() does not put in any markers, and plot() can only draw lines when there are at least two adjacent finite values.

You should postpone the plot() until after the loop.

Also, 5:3 is the same as 5:1:3 . The first element is greater than the last element and the increment (1) is positive, so the result of 5:3 is empty.

Note also that plot(VALUE1,VALUE2,VALUE3,VALUE4) would be treated more like plot(VALUE1,VALUE2), plot(VALUE3,VALUE4) -- that is, you are asking to plot i against f(i), and to plot d(i) against v(i)