MATLAB: Minimum point of Graph

gradientgraphlineminimumplot

I have plotted a parabola like curve in the rough shape of (y=x^2). How am I able to draw plot a verical line from the minimum of the graph where the gradient is zero to the x axis and have this labbled as (Xminimum). Is it also possible to obtain an x value at which this value occurs on the graph too

Thanks

Best Answer

Use the islocalmin function:

x = -5:0.1:5;
y = x.^2;
idx = islocalmin(y);
figure(1)
hold on
plot(x,y)
plot(x(idx),y(idx),'*r')
legend('Curve','Local Min')
hold off
fprintf('Min located at %0.2f\n',x(idx))

Related Solutions

MATLAB: How to plot multiple 3d on one graph

Following code works fine

interval = [-5:0.1:5];
x = -5:0.1:5;
y = -5:0.1:5; 
[X,Y] = meshgrid(x,y);
z1 = acos((cos(interval)+cos((interval).')));
z2 = acos(-(cos(interval)+cos((interval).')));
figure(1);
plot3(X,Y,z2)
hold on
plot3(X,Y,z1)

MATLAB: How find FWHM for large numbers of plots

Try this:

x=-4:5;
for k = 1:numel(x)
    z=x(k).^2;
    y(k) = z;
end
[miny,idx] = min(y);
left_x = interp1(y(1:idx),x(1:idx), y(1)/2)
right_x = interp1(y(idx:end),x(idx:end), y(1)/2)
figure
plot(x,y)
hold on
plot([left_x right_x], [1 1]*y(1)/2, '+r')
hold off

There is no ‘full width-half-maximum’ because ther is no defined maximum. This code finds the approximate values for ‘full-width-half-minimum’ instead, since only that makes sense in this context.

Best Answer

Related Solutions

MATLAB: How to plot multiple 3d on one graph

MATLAB: How find FWHM for large numbers of plots

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