How can I plot a straight line from a curve?

I want to draw a straight line across (0,0) point from the given data point.

My code with data point:

x =3:1:18;
y = [.06 .09 .115 .1288 .146 .17 .19 .224 .267 .3058 .336 .378 .491 .495 .518 .509];

plot(x,y,'-o')
grid on
hold on

Figure:

But , I want to draw a straight line.

Answer 1

[Bjorn Gustavsson]

To plot a line between a point [x_i,y_i] and [0,0] simply do this:

ph0p = plot([0,x_i],[0,y_i]);

Then you can decorate the line using the plot-handle ph0p and the set function.

For example from the fifth point in your curve this would become:

i_xy = 5;
ph0p = plot([0,x(i_xy)],[0,y(i_xy)]);

HTH

Answer 2

[Matt J]

Maybe this is what you want?

x =3:1:18;
y = [.06 .09 .115 .1288 .146 .17 .19 .224 .267 .3058 .336 .378 .491 .495 .518 .509];

p=polyfit(x,y,1);

plot(x,y,'o', x,polyval(p,x))
grid on
hold on

[Jahan N]

Thanks for your effort.Your answer is also useful.