Intercept of each line to y-line

Question

Sarfaraz Ahmed 2022-2-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1654240-intercept-of-each-line-to-y-line

编辑： DGM 2022-2-20

采纳的回答： Torsten

在 MATLAB Online 中打开

Hello folks,

I am making curve fit plot for some data and trying to make intercept point of each data line with y-line.

For examples. each line should give intercept point so there will be 10 intercept points which can be stored in any array.

I am concerning only x-axis value in the x-yline(1.5228, '--') intercept values. I tried with intercept commands but the problem is here I am dealing with objects.

I am share here code. please have a look and help in this regard, so that when I run a code it will provides x-y intercept values.

clear
close all
Data=[
0.11	0.3	0.28	0.6	0.31
0.23	0.78	0.57	1.08	0.43
0.26	0.95	0.84	1.25	0.46
0.55	1.2	1.1	1.5	0.75
6.95	7.05	8.25	7.35	7.15
5.2	4.34	4.68	4.64	5.4
4.81	4.74	4.21	5.04	5.01
3.96	4.07	3.96	4.37	4.16
3.88	3.78	3.25	4.08	4.08
2.69	2.4	2.81	2.7	2.89
2.36	2.35	2.7	2.65	2.56
2.24	2.28	2.35	2.58	2.44
1.9	2.07	1.94	2.37	2.1
1.7	1.95	1.68	2.25	1.9
0.57	1.67	1.47	1.97	0.77
0.47	0.89	1.1	1.19	0.67
];
figure(1)
plot(Data,'linewidth',1.0)
grid
legend('C1','C2','C3','C4','C5')
x=0:15;
x=x';
c1=Data(:,1);
c2=Data(:,2);
c3=Data(:,3);
c4=Data(:,4);
c5=Data(:,5);
f1 = fit(x(5:16),c1(5:16),'exp1');
f2 = fit(x(5:16),c2(5:16),'exp1');
f3 = fit(x(5:16),c3(5:16),'exp1');
f4 = fit(x(5:16),c4(5:16),'exp1');
f5 = fit(x(5:16),c5(5:16),'exp1');
figure(2)
plot(f1,'b')
hold on
plot(f2,'r')
plot(f3,'g')
plot(f4,'m')
plot(f5,'k')
yline(1.5228, '--')
grid
axis([0 17 0 7.5])
legend('C1','C2','C3','C4','C5')

Thank you.

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Torsten 2022-2-20

f1(0),...,f5(0) are the y-intercepts.

Sarfaraz Ahmed 2022-2-20

编辑：Sarfaraz Ahmed 2022-2-20

Capture.PNG

Thank you for your answer. Actually, this one for y-intercept. I want to get intercept with yline(1.5228, '--').

for example, in the attached figure intercept for "f1" is "12.492". however when I display f1 it shows y-intercept not y-line intercept. can you please let me know how can I get intercept with y-lines ? I corrected a question little bit as well.

Thank you

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Answer 1

Torsten 2022-2-20

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1654240-intercept-of-each-line-to-y-line#answer_900730

编辑：Torsten 2022-2-20

在 MATLAB Online 中打开

a = f1.a;
b = f1.b;
xintercept1 = 1/b*log(1.5228/a);

(Same for f2,f3,f4 and f5)

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Sarfaraz Ahmed 2022-2-20

Great. It helps .

Thank you so much !!

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Answer 2

DGM 2022-2-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1654240-intercept-of-each-line-to-y-line#answer_900735

编辑：DGM 2022-2-20

在 MATLAB Online 中打开

Consider the example:

Data=[

0.11 0.3 0.28 0.6 0.31

0.23 0.78 0.57 1.08 0.43

0.26 0.95 0.84 1.25 0.46

0.55 1.2 1.1 1.5 0.75

6.95 7.05 8.25 7.35 7.15

5.2 4.34 4.68 4.64 5.4

4.81 4.74 4.21 5.04 5.01

3.96 4.07 3.96 4.37 4.16

3.88 3.78 3.25 4.08 4.08

2.69 2.4 2.81 2.7 2.89

2.36 2.35 2.7 2.65 2.56

2.24 2.28 2.35 2.58 2.44

1.9 2.07 1.94 2.37 2.1

1.7 1.95 1.68 2.25 1.9

0.57 1.67 1.47 1.97 0.77

0.47 0.89 1.1 1.19 0.67

];

ymark = 1.5228; % need to be able to use this

x = (0:15).';

plotcolors = {'b','r','g','m','k'};

f = cell(size(Data,2),1);

fk = zeros(size(Data,2),2);

for kn = 1:numel(f)

f{kn} = fit(x(5:16),Data(5:16,kn),'exp1');

fk(kn,:) = coeffvalues(f{kn});

plot(f{kn},plotcolors{kn})

hold on

end

yline(ymark, '--');

grid

axis([0 17 0 7.5])

intx = log(ymark./fk(:,1))./fk(:,2); % inverse of fit function

plot(intx,ymark,'kx') % show with marker

legend('C1','C2','C3','C4','C5')

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