How to use zoomscale function in PHP mapscript

[A. Sharif]

Hello,

I am trying to create a map with a dynamic point, at a determined zoomscale.

When i use the function $oMap->zoomscale, the coordinates I have to
pass the function are the X,Y in pixels, whereas I have Longitude,
Latitude coordinates.

Is there a way to convert the Geographic coordinates to pixel
coordinates, or is a different function that will the geogrphic
coordinates and display the map at a determined scale ?

thank you,

Abdul