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vsub_c

 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.
```

```   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
```
`Fri Dec 31 18:41:15 2021`