vlcomg_c |

Table of contents## Procedurevlcomg_c ( Vector linear combination, general dimension ) void vlcomg_c ( SpiceInt n, SpiceDouble a, ConstSpiceDouble * v1, SpiceDouble b, ConstSpiceDouble * v2, SpiceDouble * sum ) ## AbstractCompute a vector linear combination of two double precision vectors of arbitrary dimension. ## Required_ReadingNone. ## KeywordsVECTOR ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- n I Dimension of vector space. a I Coefficient of `v1'. v1 I Vector in n-space. b I Coefficient of `v2'. v2 I Vector in n-space. sum O Linear vector combination a*v1 + b*v2. ## Detailed_Inputn is the dimension of `v1', `v2' and `sum'. a is the double precision scalar variable that multiplies `v1'. v1 is an arbitrary, double precision n-dimensional vector. b is the double precision scalar variable that multiplies `v2'. v2 is an arbitrary, double precision n-dimensional vector. ## Detailed_Outputsum is the double precision n-dimensional vector which contains the linear combination a * v1 + b * v2 ## ParametersNone. ## ExceptionsError free. ## FilesNone. ## ParticularsThe code reflects precisely the following mathematical expression For each value of the index `i', from 0 to n-1: sum[i] = a * v1[i] + b * v2[i] No error checking is performed to guard against numeric overflow. ## ExamplesThe numerical results shown for this example may differ across platforms. The results depend on the SPICE kernels used as input, the compiler and supporting libraries, and the machine specific arithmetic implementation. 1) Perform the projection of a 4-dimensional vector into a 2-dimensional plane in 4-space. Example code begins here. /. Program vlcomg_ex1 ./ #include <math.h> #include <stdio.h> #include "SpiceUsr.h" int main( ) { /. Local parameters. ./ #define NDIM 4 /. Local variables. ./ SpiceDouble puv [NDIM]; SpiceDouble v [NDIM]; /. Let `x' be an arbitrary NDIM-vector ./ SpiceDouble x [NDIM] = { 4.0, 35.0, -5.0, 7.0 }; /. Let `u' and `v' be orthonormal NDIM-vectors spanning the plane of interest. ./ SpiceDouble u [NDIM] = { 0.0, 0.0, 1.0, 0.0 }; v[0] = sqrt(3.0)/3.0; v[1] = -sqrt(3.0)/3.0; v[2] = 0.0; v[3] = sqrt(3.0)/3.0; /. Compute the projection of `x' onto this 2-dimensional plane in NDIM-space. ./ ## Restrictions1) No error checking is performed to guard against numeric overflow or underflow. The user is responsible for insuring that the input values are reasonable. ## Literature_ReferencesNone. ## Author_and_InstitutionJ. Diaz del Rio (ODC Space) W.L. Taber (JPL) ## Version-CSPICE Version 1.0.1, 13-AUG-2021 (JDR) Edited the header to comply with NAIF standard. Added complete code example based on existing example. -CSPICE Version 1.0.0, 30-JUN-1999 (WLT) ## Index_Entrieslinear combination of two n-dimensional vectors |

Fri Dec 31 18:41:15 2021