How to link two given points and add isolines to a plot?

Hi, everyone. I need some help to draw a plot with differnt kinds of lines. A case of the plot can be seen in the figure. It is very easy to draw the red, blue and green soild lines. However , I do not know how to draw the red, blue and green dash lines when I already know the starting and ending coordinations of these dash lines? If possible, Could anyone tell me how to draw the other two black dash lines. The two black dash lines are isolines and their values can be given freely.

[Walter Roberson]

plot(x, y, '--g')

Answer 1

[KSSV]

It looks like you have three curves i.e three different set of (x,y) arrays corresponding to Red, Blue and Green. Also you three points (xx,yy) corresponding to R, B and G.

hold on
plot([xx x(1)],[yy y(1)],'--k')
plot([xx x(end)],[yy y(end)],'--k')

[Genhou SUN]

Thanks a lot. It works.

I wonder could you help me with how to add the isolines to this plot. One isoline increases from 0.005 to 0.04 from right to the left and the other isoline decreases from 935mba to 535mba from left to right.

The two isolines seem to be contour lines, but I fail to figure out how to add the two isolines to this plot. Thanks a lot in advance.