x-intersection of part of extended line from curve
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Hello There.
I have plot which looks below. Part of curve which behave like straight line such as red highlighted part. I want extend this red line and find time when it intersects with horizonal axis (Time).
The initial code is provided with redline part. I will be using this method to analyses many other similar types of graphs.
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Star Strider
2020-8-12
Add these lines to your code after the ‘m’ calculation and before figure(1):
B = [TC ones(size(TC))] \ IC; % Fit Red Line (Estimate Parameters)
Slope = B(1);
YIntercept = B(2);
XIntercept = -YIntercept / Slope % Calculate X-Intercept
ExtLine = [[TC(1); XIntercept] ones(size(TC))] * B % Y-Coordinates
and after the first hold call:
plot([TC(1); XIntercept], ExtLine, '-g') % Plot Line
The x-intercept is 1.4494 microseconds.
.
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Star Strider
2020-8-13
Correct. That was a typo on my part. (Still too early for me here!) They are labeled correctly in my code. The angles were calculated from the ‘Slope’ variable, so they are correct.
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Alan Stevens
2020-8-12
编辑:Alan Stevens
2020-8-12
You can use the following relation:
( max(y_redline_value) - min(y_redline_value) ) / ( max(x_redline_value) - min(x_redline_value) )=
( max(y_redline_value) - 0 ) / ( max(x_redline_value) - x_desired )
Rearrange to get x_desired (i.e. the value of the straight line intercept on the x-axis).
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