vdist_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

```   SpiceDouble vdist_c ( ConstSpiceDouble v1,
ConstSpiceDouble v2 )

```

#### Abstract

```   Return the distance between two three-dimensional vectors.
```

```   None.
```

#### Keywords

```   VECTOR

```

#### Brief_I/O

```   Variable  I/O  Description
--------  ---  --------------------------------------------------

v1,
v2         I   Two 3-vectors.

The function returns the distance between v1 and v2.
```

#### Detailed_Input

```   v1,
v2         are two vectors in three-dimensional space, the
distance between which is desired.
```

#### Detailed_Output

```   The function returns the distance between v1 and v2.  This is
defined as

||  v1 - v2  ||,

where || x || indicates the Euclidean norm of the vector x.
```

#### Parameters

```   None.
```

#### Exceptions

```   Error free.
```

#### Files

```   None.
```

#### Particulars

```   This function is simply shorthand for the code

vsub_c ( v1, v2, diff );

dist = vnorm_c ( diff );

Using this function saves you the annoyance of declaring local
storage for the difference vector diff.

The Euclidean norm of a three-dimensional vector (x, y, z) is
defined as

1/2
2        2        2
(   x    +   y    +   z    ).

This number is the distance of the point (x, y, z) from the
origin.  If A and B are two vectors whose components are

( A(1), A(2), A(3) )    and    ( B(1), B(2), B(3) ),

then the distance between A and B is the norm of the difference
A - B, which has components

(  A(1) - B(1),  A(2) - B(2),  A(3) - B(3)  ).

A related routine is vdistg_, which computes the distance between
two vectors of general dimension.
```

#### Examples

```   1)  If v1 is

( 2.0,  3.0,  0. )

and v2 is

( 5.0,  7.0,  12. ),

vdist_c (v1, v2) will be 13..

2)  If VGR2 and NEP are states of the Voyager 2 spacecraft and
Neptune with respect to some common center at a given time
ET, then

vdist_c ( VGR2, NEP )

yields the distance between the spacecraft and Neptune at time
ET.
```

#### Restrictions

```   None.
```

#### Literature_References

```   None.
```

#### Author_and_Institution

```   N.J. Bachman   (JPL)
```

#### Version

```   -CSPICE Version 1.2.0, 22-OCT-1998 (NJB)

Made input vectors const.  Removed #include of SpiceZfc.h.

-CSPICE Version 1.1.0, 06-MAR-1998   (EDW)

Removed non printing character.

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

#### Index_Entries

```   distance between 3-dimensional vectors
```
`Wed Apr  5 17:54:46 2017`