frame_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

```   void frame_c ( SpiceDouble x,
SpiceDouble y,
SpiceDouble z )

```

#### Abstract

```
Given a vector x, this routine builds a right handed
orthonormal frame x,y,z where the output x is parallel to
the input x.
```

```
None.
```

#### Keywords

```
AXES,  FRAME

```

#### Brief_I/O

```
VARIABLE  I/O  DESCRIPTION
--------  ---  ------------------------------------------------
x         I/O  Input vector. A parallel unit vector on output.
y          O   Unit vector in the plane orthogonal to x.
z          O   Unit vector given by x X y.
```

#### Detailed_Input

```

x      This vector is used to form the first vector of a
right-handed orthonormal triple.
```

#### Detailed_Output

```
x,
y,
z      form a right handed orthonormal frame, where x is
now a unit vector parallel to the original input
vector x.  There are no special geometric properties
connected to y and z (other than that they complete the
right handed frame).
```

```
None.
```

#### Exceptions

```
Error Free.

1) If x on input is the zero vector the ``standard'' frame (ijk)
is returned.
```

```
None.
```

#### Particulars

```
Given an input vector x, this routine returns unit vectors x,
y, and z such that xyz forms a right-handed orthonormal frame
where the output x is parallel to the input x.

This routine is intended primarily to provide a basis for
the plane orthogonal to x.  There are no special properties
associated with y and z other than that the resulting xyz frame
is right handed and orthonormal.  There are an infinite
collection of pairs (y,z) that could be used to this end.
Even though for a given x, y and z are uniquely determined, users
should regard the pair (y,z) as a random selection from this
infinite collection.

For instance, when attempting to determine the locus of points
that make up the limb of a triaxial body, it is a straightforward
matter to determine the normal to the limb plane.  To find
the actual parametric equation of the limb one needs to have
a basis of the plane.  This routine can be used to get a basis
in which one can describe the curve and from which one can
then determine the principal axes of the limb ellipse.
```

#### Examples

```
In addition to using a vector to construct a right handed frame
with the x-axis aligned with the input vector, one can construct
right handed frames with any of the axes aligned with the input
vector.

For example suppose we want a right hand frame xyz with the
z-axis aligned with some vector v.  Assign v to z

z = v;
z = v;
z = v;

Then call frame_c with the arguments x,y,z cycled so that z
appears first.

frame_c (z, x, y);

The resulting xyz frame will be orthonormal with z parallel
to the vector v.

To get an xyz frame with y parallel to v perform the following

y = v;
y = v;
y = v;

frame_c (y, z, x);
```

```
None.
```

```
None.
```

#### Author_and_Institution

```
W.L. Taber      (JPL)
I.M. Underwood  (JPL)
```

#### Version

```
-CSPICE Version 1.0.0, 26-MAR-1999 (NJB)
```

#### Index_Entries

```
build a right handed coordinate frame
```
`Wed Apr  5 17:54:35 2017`