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Index Page vsubg_c

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Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       vsubg_c ( Vector subtraction, general dimension )

       void vsubg_c ( ConstSpiceDouble  * v1,
                      ConstSpiceDouble  * v2,
                      SpiceInt            ndim,
                      SpiceDouble       * vout )

#### Abstract

       Compute the difference between two double precision vectors of
       arbitrary dimension.

#### Required_Reading

       None.

#### Keywords

       VECTOR

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       v1         I   First vector (minuend).
       v2         I   Second vector (subtrahend).
       ndim       I   Dimension of `v1', `v2', and `vout'.
       vout       O   Difference vector, v1 - v2.

#### Detailed_Input

       v1          is a double precision vector of arbitrary dimension which
                   is the minuend (i.e. first or left-hand member) in the
                   vector subtraction.

       v2          is a double precision vector of arbitrary dimension which
                   is the subtrahend (i.e. second or right-hand member) in
                   the vector subtraction.

       ndim        is the dimension of `v1' and `v2' (and `vout').

#### Detailed_Output

       vout        is a double precision n-dimensional vector which
                   represents the vector difference, v1 - v2. `vout' may
                   overwrite `v1' or `v2'.

#### Parameters

       None.

#### Exceptions

       Error free.

#### Files

       None.

#### Particulars

       For each value of the index `i' from 0 to ndim-1, this function
       performs the following subtraction:

          vout[i] = v1[i] - v2[i]

       No error checking is performed to guard against numeric overflow
       or underflow. `vout' may overwrite `v1' or `v2'.

#### Examples

       The 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) Define two sets of n-dimensional vectors and compute the
          difference from each vector in first set with the
          corresponding vector in the second set.

          Example code begins here.

          /.
             Program vsubg_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local parameters.
             ./
             #define NDIM         4
             #define SETSIZ       3

             /.
             Local variables.
             ./
             SpiceDouble          vout   [NDIM];

             SpiceInt             i;

             /.
             Define the two vector sets.
             ./
             SpiceDouble          v1     [SETSIZ][NDIM] = {
                                       {1.0,  2.0,  3.0,  4.0},
                                       {1.0,  2.0,  3.0,  4.0},
                                       {1.0,  2.0,  3.0,  4.0} };

             SpiceDouble          v2     [SETSIZ][NDIM] = {
                                       { 1.0,  1.0,  1.0,  1.0},
                                       {-1.0, -2.0, -3.0, -4.0},
                                       {-1.0,  2.0, -3.0,  4.0} };

             /.
             Calculate the difference between each pair of vectors
             ./
             for ( i = 0; i < SETSIZ; i++ )
             {

                vsubg_c ( v1[i], v2[i], NDIM, vout );

                printf( "First vector :  %5.1f %5.1f %5.1f %5.1f\n",
                              v1[i][0], v1[i][1], v1[i][2], v1[i][3] );
                printf( "Second vector:  %5.1f %5.1f %5.1f %5.1f\n",
                              v2[i][0], v2[i][1], v2[i][2], v2[i][3] );
                printf( "Difference   :  %5.1f %5.1f %5.1f %5.1f\n",
                                  vout[0], vout[1], vout[2], vout[3] );
                printf( "\n" );

             }

             return ( 0 );
          }

          When this program was executed on a Mac/Intel/cc/64-bit
          platform, the output was:

          First vector :    1.0   2.0   3.0   4.0
          Second vector:    1.0   1.0   1.0   1.0
          Difference   :    0.0   1.0   2.0   3.0

          First vector :    1.0   2.0   3.0   4.0
          Second vector:   -1.0  -2.0  -3.0  -4.0
          Difference   :    2.0   4.0   6.0   8.0

          First vector :    1.0   2.0   3.0   4.0
          Second vector:   -1.0   2.0  -3.0   4.0
          Difference   :    2.0   0.0   6.0   0.0

#### Restrictions

       1)  No error checking is performed to guard against numeric
           overflow. The programmer is thus required to insure that the
           values in `v1' and `v2' are reasonable and will not cause
           overflow. No error recovery or reporting scheme is
           incorporated in this routine.

       2)  It is assumed the proper amount of memory has been allocated for
           `v1', `v2' and `vout'.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman        (JPL)
       J. Diaz del Rio     (ODC Space)
       W.M. Owen           (JPL)
       E.D. Wright         (JPL)

#### Version

       -CSPICE Version 1.1.1, 05-JUL-2021 (JDR)

           Edited the header to comply with NAIF standard. Added complete
           code example based on existing example.

       -CSPICE Version 1.1.0, 22-OCT-1998 (NJB)

           Made input vectors const.

       -CSPICE Version 1.0.0, 05-MAR-1998 (EDW) (WMO)

#### Index_Entries

       n-dimensional vector subtraction

#### Link to routine vsubg_c source file vsubg_c.c

    Fri Dec 31 18:41:15 2021