cspice_vprjp

 Abstract I/O Examples Particulars Required Reading Version Index_Entries

#### Abstract

```
CSPICE_VPRJP orthogonally projects a vector onto a specified plane.

```

#### I/O

```
Given:

vin     the vector to orthogonally project onto a specified plane.

[3,1] = size(vin); double = class(vin)

plane   a structure describing a SPICE plane onto which to
project 'vin'.

[1,1] = size(plane); struct = class(plane)

The structure has the fields:

normal:     [3,1] = size(normal); double = class(normal)
constant:   [1,1] = size(constant); double = class(constant)

the call:

vout = cspice_vprjp( vin, plane )

returns:

vout   the vector resulting from the orthogonal projection of 'vin'
onto 'plane'. 'vout' is the closest point in the specified
plane to 'vin'.

[3,1] = size(vout); double = class(vout)

```

#### Examples

```
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.

%
% Find the closest point in the ring plane of a planet to a
% spacecraft located at vec1 (in body-fixed coordinates).
%
vec1 = [ -5., 7., 2.2]';

%
% Define the vector normal as the normal to the
% equatorial ring plane, and the origin at body/ring center
%
norm = [ 0., 0., 1. ]';
orig = [ 0., 0., 0. ]';

%
% Create the plane structure.
%
ring_plane = cspice_nvp2pl( norm, orig );

%
% Project the position vector onto the ring plane...
%
proj = cspice_vprjp( vec1, ring_plane )

MATLAB outputs:

proj =

-5
7
0

```

#### Particulars

```
Projecting a vector v orthogonally onto a plane can be thought of
as finding the closest vector in the plane to v.  This `closest
vector' always exists; it may be coincident with the original
vector.

Two related routines are cspice_vprjpi, which inverts an orthogonal
projection of a vector onto a plane, and cspice_vproj, which projects
a vector orthogonally onto another vector.

```

```
For important details concerning this module's function, please refer to
the CSPICE routine vprjp_c.

MICE.REQ

```

#### Version

```
-Mice Version 1.0.1, 18-DEC-2014, EDW (JPL)

Edited I/O section to conform to NAIF standard for Mice documentation.

-Mice Version 1.0.0, 27-AUG-2012, EDW (JPL)

```

#### Index_Entries

```
vector projection onto plane

```
`Wed Apr  5 18:00:36 2017`