vlax-curve-getfirstderiv


(vlax-curve-getfirstderiv curveEnt param)

This function returns the "first derivative" vector of curveEnt curve entity at specified param parameter.

Arguments

curveEnt  (ename or vla-object) the COM object of any "curve" entity
param  (integer or double)  the "parameter" on the curve

Return

vector (point list);  the vector of first derivative of curve at specified parameter, or NIL

Example

(setq vlaCircle (vlax-ename->vla-object (entlast)))  #<VLA-OBJECT IAcadCircle 000000003A012150>
(vlax-curve-getfirstderiv vlaCircle 0.75)  (-171.472816549062 184.063405049173 0.0)

Remarks



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