Draw a tangent line with a given slope in Log scale

Dear all,

I have a graph datapoints loaded in MATLAB. Y axis is Voltage (E) and x-axis is in Log scale. I have to draw a tangent line to this curve with a given of 50 V/dec in MATLAB. I also need to find the point where the tangent line crosses the curve. I appreciate that if someone could help.

I really appreciate your help in advance.

Answer 1

[Sulaymon Eshkabilov]

To compute the tangent line of this curve, I would do the followings:

(1) Get the numerical data of the curve (shown in your plotted Figure)

(2) Find the polynomial (quadratic) fit model E(x) formulation using, e.g.: fit() or polyfit() or ...

(3) Take a symbolic derivative of E(x) formulation => dE(x)

(4) Compute dE(50) and E(50)

(5) Plug in the computed values in step 5 into this equation: y = dE(50)*(x-50) + E(50). This would be the tangent line equation for that point of x = 50.

(6) Plot the found tangent line data along with the original curve data.

[Mohiedin Bagheri]

Thank you @Sulaymon Eshkabilov for your reply. Is there anyway to do it without doing the polynomial fit? I mean directly draw a line with the slope of 50 mV/dec in log scale . Below you can find my data in .m file. I appreciate your guidance in advance Sulaymon

Thanks

[Image Analyst]

@Mohiedin Bagheri, make it easy for people to help you not hard. That means first reading the posting guidelines:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

and then secondly, you will then know that you were supposed to attach your data. Don't force people to make code to somehow create data similar to yours when you already have it. Just attach your variable in a .mat file with the paperclip icon.

[Mohiedin Bagheri]

@Sulaymon Eshkabilov attached is my .m file data. Thank you