6.3. strans functions

6.3. `strans` functions
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6.3. `strans` functions #

6.3.1. Converting to ZXZ
6.3.2. Angles and axes

6.3.1. Converting to ZXZ #

Using the function strans_zxz(strans), you can convert an Euler transformation to ZXZ axes transformation.

Example 6.5. Change the transformation axes to ZXZ

Convert the transformation strans '20d, -270d, 70.5d, XZY' to a ZXZ transformation.

sql> SELECT strans_zxz ( strans '20d, -270d, 70.5d, XZY' );

6.3.2. Angles and axes #

It is possible to get the components of an Euler transformation.

Table 6.1. Getting Euler transformation attributes

function	description
`phi`	first angle of a transformation
`theta`	second angle of a transformation
`psi`	third angle of a transformation
`axes`	transformation axes as a three letter code

The angles will always returned as a float8 value in radians. The axes are returned as a three letter code.

Example 6.6. Get the second axis and its rotation angle

sql> SELECT theta( strans '20d,30d,40d,XZY' ) * 180 / pi() AS theta;
 theta
-------
 30
(1 row)
sql> SELECT substring ( axes ( strans '20d,30d,40d,XZY' ) from 2 for 1 ) AS axis;
 axis
------
  Z
(1 row)