pl2psv_c |

## Procedurevoid pl2psv_c ( ConstSpicePlane * plane, SpiceDouble point[3], SpiceDouble span1[3], SpiceDouble span2[3] ) ## AbstractReturn a point and two orthogonal spanning vectors that generate a specified plane. ## Required_ReadingPLANES ## KeywordsGEOMETRY MATH PLANE ## Brief_I/OVariable I/O Description -------- --- -------------------------------------------------- plane I A CSPICE plane. point, span1, span2 O A point in the input plane and two vectors spanning the input plane. ## Detailed_Inputplane is a CSPICE plane that represents the geometric plane defined by point, span1, and span2. ## Detailed_Outputpoint, span1, span2 are, respectively, a point and two orthogonal spanning vectors that generate the geometric plane represented by plane. The geometric plane is the set of vectors point + s * span1 + t * span2 where s and t are real numbers. point is the closest point in the plane to the origin; this point is always a multiple of the plane's normal vector. span1 and span2 are an orthonormal pair of vectors. point, span1, and span2 are mutually orthogonal. ## ParametersNone. ## ExceptionsError free. 1) The input plane MUST have been created by one of the CSPICE routines nvc2pl_c ( Normal vector and constant to plane ) nvp2pl_c ( Normal vector and point to plane ) psv2pl_c ( Point and spanning vectors to plane ) Otherwise, the results of this routine are unpredictable. ## FilesNone. ## ParticularsCSPICE geometry routines that deal with planes use the `plane' data type to represent input and output planes. This data type makes the subroutine interfaces simpler and more uniform. The CSPICE routines that produce CSPICE planes from data that define a plane are: nvc2pl_c ( Normal vector and constant to plane ) nvp2pl_c ( Normal vector and point to plane ) psv2pl_c ( Point and spanning vectors to plane ) The CSPICE routines that convert CSPICE planes to data that define a plane are: pl2nvc_c ( Plane to normal vector and constant ) pl2nvp_c ( Plane to normal vector and point ) ## Examples1) Find the intersection of a plane and the unit sphere. This is a geometry problem that arises in computing the intersection of a plane and a triaxial ellipsoid. The CSPICE routine inedpl_c computes this intersection, but this example does illustrate how to use this routine. /. The geometric plane of interest will be represented by the CSPICE plane plane in this example. The intersection circle will be represented by the vectors center, v1, and v2; the circle is the set of points center + cos(theta) v1 + sin(theta) v2, where theta is in the interval (-pi, pi]. The logical variable found indicates whether the intersection is non-empty. The center of the intersection circle will be the closest point in the plane to the origin. This point is returned by ## RestrictionsNone. ## Literature_References[1] `Calculus and Analytic Geometry', Thomas and Finney. ## Author_and_InstitutionN.J. Bachman (JPL) ## Version-CSPICE Version 1.0.0, 05-MAR-1999 (NJB) ## Index_Entriesplane to point and spanning vectors |

Wed Apr 5 17:54:40 2017