Image Pan Movement Actionscript

programming flash
1

Hi, could someone help me please. I got the following Action Script for my image-movement. How can i make the movement to slow down at the end? Thx for your help!

drag = “/dragControl”;

/:w = getProperty("/nav", _width);
/:xPos = getProperty(drag, _x);
/:xPos = /:xPos-640;
setProperty("/nav", _x, getProperty("/nav", _x)-(/:xPos/92));
if (Number(getProperty("/nav", _x))<Number(-(/:w/2))) {
setProperty("/nav", _x, 0.01);
} else if (Number(getProperty("/nav", _x))>710) {
setProperty("/nav", _x, 710);
} else if (Number(getProperty("/nav", _x))<580) {
setProperty("/nav", _x, 580);
}