rotmat_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 rotmat_c ( ConstSpiceDouble   m1,
SpiceDouble        angle,
SpiceInt           iaxis,
SpiceDouble        mout )

```

#### Abstract

```
rotmat_c applies a rotation of angle radians about axis iaxis to a
matrix.  This rotation is thought of as rotating the coordinate
system.
```

```
None.
```

#### Keywords

```
MATRIX,  ROTATION

```

#### Brief_I/O

```
VARIABLE  I/O  DESCRIPTION
--------  ---  --------------------------------------------------
m1        I     Matrix to be rotated.
angle     I     Angle of rotation (radians).
iaxis     I     Axis of rotation (X=1, Y=2, Z=3).
mout      O     Resulting rotated matrix.
```

#### Detailed_Input

```
m1      This is a matrix to which a rotation is to be applied.
In matrix algebra, the components of the matrix are
relative to one particular coordinate system. Applying
rotmat_c changes the components of m1 so that they are
relative to a rotated coordinate system.

angle   The angle in radians through which the original
coordinate system is to be rotated.

iaxis   An index for the axis of the original coordinate system
about which the rotation by angle is to be performed.
iaxis = 1,2 or 3 designates the x-, y- or z-axis,
respectively.
```

#### Detailed_Output

```
mout    The matrix resulting from the application of the
specified rotation to the input matrix m1.  If

[angle]
iaxis

(see the Rotations Required Reading document) then mout is
given by the following matrix equation:

mout = [angle]      * m1
iaxis

mout can overwrite m1.
```

```
None.
```

#### Exceptions

```
Error free.

1) If the axis index is not in the range 1 to 3 it will be
treated the same as that integer 1, 2, or 3 that is congruent
to it mod 3.
```

```
None.
```

```
None.
```

#### Examples

```
Suppose that to rotate the a set of inertial axes to body fixed
axes, one must first roll the coordinate axes about the x-axis by
angle r to get x', y', z'.  From this one must pitch about the
y' axis by angle o to get x'', y'', z''.  And finally yaw the
x'', y'', z'' about the z'' axis by angle y to obtain the
transformation to bodyfixed coordinates.  If id is the identity
matrix, then the following code fragment generates the
transformation from interitial to body fixed.

rotmat_c ( id, r, 1, m1   );
rotmat_c ( m1, p, 2, m2   );
rotmat_c ( m2, y, 3, tibf );
```

```
None.
```

```
None.
```

#### Author_and_Institution

```
N.J. Bachman    (JPL)
W.M. Owen       (JPL)
W.L. Taber      (JPL)
```

#### Version

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

```
`Wed Apr  5 17:54:42 2017`