Find points are located at a radial distance of 20m from a point

I have an ascii file, with two columns. The first has Latitude and the second has longtitude. Also I have one point (lets call it "MYPOINT") with spesific latitde and longtitude. I would like with the base of MYPOINT to find all the point in the radious/cirle distance of 20km (For example from the 100 points, the points that are located at a radial distance of 20m from the MYPOINT.

Which functions should I use?

Answer 1

[Cris LaPierre]

Generate the points that make up the circle around myPoint, then use the inpolygon function to identify the points that are within the circle.

[Ivan Mich]

well, I use this function:

(deg2km(distance(lat1,lon1,lat,lon)))

In order to calculate distance between MYPOINT and several point. I would like to keep only the point that have distance between 5 and 20km from MYPOINT .

What modifications should I make in my script?

[Ivan Mich]

lat1, lon1, coordinates from several points and lat lon the coordinates from my stable point (MYPOINT)

[Cris LaPierre]

I know nothing about your script, and inpolygon now nothing about units. Look at the examples in the linked page for inpolygon and adapt to work with your data.