how to extend a straight line passing through two points until it meets the y axis of the Cartesian plane

I have a graph of this type and I have created the straight line dashed in red that passes through the point of coordinates 0-0 and the point marked with the red dot. now I should extend this line until it meets the y axis, always maintaining the same inclination as the straight line. this is because then I need to identify the coordinates of the points of intersection between the straight line and the other curved lines with values 10 - 1 and 0.01.

how can I do? can anyone help me?

[dpb]

Attach data and code so folks have something to work with...nothing can do with just the image...

[Ghazwan]

It looks like you are doing this manually. It is way better to make a code for this line. With the code, we can make an equation for and find the intersection points.

Answer 1

[Star Strider]

It already meets the y-axis at the origin (0,0).

If you want to extend it to , that is straightforward —

slope = -53634 / -234311;
intercept = 0;

yfit = -5E+5*slope + intercept

yfit = -1.1445e+05

figure
plot([-5E+5 0], [yfit 0], '--r')
grid
axis([-5E+5 1E+5  -3.1E+5  2.5E+5])

I do not have your contourf plot, so I cannot plot it with that as well.

.

[ELISABETTA BILLOTTA]

thank you!!! works!!!

[Star Strider]

As always, my pleasure!

Answer 2

[Image Analyst]

Is this like what you want?

x = [1, 5];
y = [2, 7];
plot(x, y, 'b.-', 'LineWidth', 2, 'MarkerSize', 30)
grid on;
xlim([0, 6])
ylim([0, 8])
% Fit a line through x and y
coefficients = polyfit(x, y, 1);
% Get the value on the y axis, which is when x=0.
x0 = 0;
y0 = polyval(coefficients, x0)

y0 = 0.7500

% Plot a line from the y axis to the point [x1, y1]
hold on;
plot([x0, x(1)], [y0, y(1)], 'r-', 'LineWidth', 2)