(vlax-curve-getParamAtDist ename distance)
The vlax-curve-getParamAtDist function calculates the value of the parameter at a point that is on a curve and at a specified distance from the starting point.
ename specifies an entity to be evaluated.
distance is a floating-point number specifying the distance from the beginning of the entity.
The function returns the value of the parameter as floating-point number. If the function fails, it returns nil.
Example
: (setq en (entlast))
<EName: 045d4b64>
: (vlax-curve-getParamAtDist en 1.0)
0.685049