How can I interpolate x and y data points in plot and slope (dy/dx) at any value of x?

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MOHD UWAIS 2023-2-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1919960-how-can-i-interpolate-x-and-y-data-points-in-plot-and-slope-dy-dx-at-any-value-of-x

编辑： Torsten 2023-2-27

采纳的回答： Torsten

clear all

clc

x=[15 20 25 30 35 40 45 50 55];

y=[11.89 11.845 11.85 11.855 11.865 11.93 12.01 12.2 12.77];

plot(x,y)

采纳的回答

Torsten 2023-2-27

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1919960-how-can-i-interpolate-x-and-y-data-points-in-plot-and-slope-dy-dx-at-any-value-of-x#answer_1181085

编辑：Torsten 2023-2-27

在 MATLAB Online 中打开

x=[15 20 25 30 35 40 45 50 55];

y=[11.89 11.845 11.85 11.855 11.865 11.93 12.01 12.2 12.77];

% Approximate dy/dx

dy = gradient(y,5);

hold on

yyaxis left

plot(x,y)

ylabel('y vs. x')

yyaxis right

plot(x,dy)

ylabel('dy/dx vs. x')

hold off

grid on

% interpolate y and dy/dx at x=x0

x0 = 22;

y0 = interp1(x,y,x0)

y0 = 11.8470

dy0 = interp1(x,dy,x0)

dy0 = -0.0020

But you also didn't give us an equation for y in terms of x ... So isn't it natural that you also only get dy/dx as a vector of 9 values from the command dy = gradient(y,5) and that you have to interpolate between the values to get y and dy/dx for some given value of x in between 15 and 55 ?

MOHD UWAIS 2023-2-27