how to calculate slope of a particular point

i want to calculate the slope of the of the marked region with reactangular boxes . please suuggest me how it can be done

Answer 1

[Star Strider]

Use the gradient function to calculate the derivative. If you want to fit a line to it, use the polyfit (and related functions).

For example:

b = polyfit(x,y,1);

The slope will be ‘b(1)’.

[Manish Kumar]

But how i can get the slope for particular region like i marked the region with rectangular boxes

[Star Strider]

You have to get the indices of the relevant parts of ‘V’. I would use find:

idx = find(V < 8);
b1 = polyfit(V(idx), I(idx), 1);
idx = find(V > 38);
b2 = polyfit(V(idx), I(idx), 1);

The slopes will be ‘b1(1)’ and ‘b2(1)’.

[Manish Kumar]

thanks you so much i got the answer

[Star Strider]

As always, My pleasure.