Show derivatives vector on a plot.

I've a curve plotted by the command plot(xx,oo) where xx and oo are coefficients obtained with Hermite interpolation method.

Now i want to show a little vector corresponding of some points (that i know) on the curve, that shows the derivative direction in these points.

Thank you

Answer 1

[Bjorn Gustavsson]

Just use arrow or arrow3 with start-point at the corresponding point and end [dx,dy] away.

arrow function on the FEX

arrow3 function on the FEX

[Antonio]

Thank you but i think i have not well explained my problem.

I have a set of points P_i=(x_i,y_i) taken from a curve F(t)=(x(t),y(t)) . For each of these points i know the derivatives values (dx_i,dy_i) and i'd like to show the derivative's vector for which i already know them values (dx_i,dy_i).

Can i please have an example? (sorry 4 my bad english)

[Antonio]

SOLVED ;)

c=diff(oo)./diff(pp);
c=[c,0];
d=0.3;
n=length(pp);

for i=1:n
     rx = [pp(i)-d/2:0.1:pp(i)+d/2];
     ry = zeros(1, length(rx));
     for k=1:length(rx)
         ry(k) = oo(i) + c(i)*(rx(k)-pp(i));
     end

     plot(rx, ry, 'red')
end