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Index Page vsub_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

       vsub_c ( Vector subtraction, 3 dimensions )

       void vsub_c ( ConstSpiceDouble   v1[3],
                     ConstSpiceDouble   v2[3],
                     SpiceDouble        vout[3] )

#### Abstract

       Compute the difference between two double precision 3-dimensional
       vectors.

#### Required_Reading

       None.

#### Keywords

       VECTOR

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       v1         I   First vector (minuend).
       v2         I   Second vector (subtrahend).
       vout       O   Difference vector, v1 - v2.

#### Detailed_Input

       v1          is a double precision 3-dimensional vector which is the
                   minuend (i.e. first or left-hand member) in the vector
                   subtraction.

       v2          is a double precision 3-dimensional vector which is the
                   subtrahend (i.e. second or right-hand member) in the
                   vector subtraction.

#### Detailed_Output

       vout        is a double precision 3-dimensional vector which
                   represents the vector difference, v1 - v2. `vout' may
                   overwrite either `v1' or `v2'.

#### Parameters

       None.

#### Exceptions

       Error free.

#### Files

       None.

#### Particulars

       For each value of the index `i' from 0 to 2, this routine performs
       the following subtraction:

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

       No error checking is performed to guard against numeric overflow
       or underflow.

#### 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 3-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 vsub_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local parameters.
             ./
             #define SETSIZ       3

             /.
             Local variables.
             ./
             SpiceDouble          vout   [3];

             SpiceInt             i;

             /.
             Define the two vector sets.
             ./
             SpiceDouble          v1     [SETSIZ][3] = {
                                       {1.0,  2.0,  3.0},
                                       {1.0,  2.0,  3.0},
                                       {1.0,  2.0,  3.0} };

             SpiceDouble          v2     [SETSIZ][3] = {
                                       { 1.0,  1.0,  1.0},
                                       {-1.0, -2.0, -3.0},
                                       {-1.0,  2.0, -3.0} };

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

                vsub_c ( v1[i], v2[i], vout );

                printf( "First vector :  %5.1f %5.1f %5.1f\n",
                              v1[i][0], v1[i][1], v1[i][2] );
                printf( "Second vector:  %5.1f %5.1f %5.1f\n",
                              v2[i][0], v2[i][1], v2[i][2] );
                printf( "Difference   :  %5.1f %5.1f %5.1f\n",
                                  vout[0], vout[1], vout[2] );
                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
          Second vector:    1.0   1.0   1.0
          Difference   :    0.0   1.0   2.0

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

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

#### Restrictions

       1)  The user is required to determine that the magnitude each
           component of the vectors is within the appropriate range so as
           not to cause floating point overflow. No error recovery or
           reporting scheme is incorporated in this routine.

#### 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 1.1.2, 05-JUL-2021 (JDR)

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

       -CSPICE Version 1.1.1, 07-NOV-2003 (EDW)

           Corrected a mistake in the second example's value
           for VOUT, i.e. replaced [1D24, 2D23, 0.0] with
           [-1e24, 0.0, 0.0].

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

           Made input vectors const.

       -CSPICE Version 1.0.0, 08-FEB-1998 (EDW) (WMO)

#### Index_Entries

       3-dimensional vector subtraction

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

    Fri Dec 31 18:41:15 2021