## skyview.geometry Class Transformer

```java.lang.Object
skyview.geometry.Transformer
```
All Implemented Interfaces:
java.io.Serializable, Component
Direct Known Subclasses:
Converter, Deprojecter, Distorter, Projecter, Rotater, Scaler, SphereDistorter

`public abstract class Transformerextends java.lang.Objectimplements Component`

The Transformer class is the superclass for a variety of classes that transform positions represented in one frame to another. The subclasses of Transformer include:

• Projecter 3/2: Transform celestial coordinates to a projection plane.
• Deprojecter 2/3: Transform coordinates in a projection plane to the celestial sphere.
• Rotater 3/3: Rotate coordinates in the celestial sphere
• SphereDistorter 3/3: Non-linear transformations in the celestial sphere.
• Distorter 2/2: Non-linear transformations in the projection plane
• Scaler 2/2: Affine transformations in the projection plane
• Converter: Apply a series of conversions in turn. The numbers after the type indicate the dimensionality of the input/output.

Serialized Form

Constructor Summary
`Transformer()`

Method Summary
`protected abstract  int` `getInputDimension()`
Get the dimensionality of the input vectors.
`protected abstract  int` `getOutputDimension()`
Get the dimensionality of the output vectors.
`abstract  Transformer` `inverse()`
Get the inverse of the transformation.
`abstract  boolean` `isInverse(Transformer trans)`
Are these two transformations, inverses of each other? This method is used to optimize a series of transformations where transformations.
` double[]` `transform(double[] in)`
Convert a single point.
` void` ```transform(double[][] in, double[][] out)```
Convert an array of points where the output vectors are supplied.
`abstract  void` ```transform(double[] in, double[] out)```
Convert a single point where the output vector is supplied.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface skyview.Component
`getDescription, getName`

Constructor Detail

### Transformer

`public Transformer()`
Method Detail

### getOutputDimension

`protected abstract int getOutputDimension()`
Get the dimensionality of the output vectors.

### getInputDimension

`protected abstract int getInputDimension()`
Get the dimensionality of the input vectors.

### transform

`public double[] transform(double[] in)`
Convert a single point. This method creates a new object and is not recommended when high throughput is needed.

Parameters:
`in` - An array giving the input vector.
Returns:
An array giving the transformed vector. For projections and deprojections this will have a different dimension

### inverse

```public abstract Transformer inverse()
throws TransformationException```
Get the inverse of the transformation. If the order matters, then the inverse is to be applied after the original transformation. This is primarily an issue with Converters.

Throws:
`TransformationException`

### transform

```public abstract void transform(double[] in,
double[] out)```
Convert a single point where the output vector is supplied.

Parameters:
`in` - The input vector.
`out` - The output vector, it may be the same as the input vector if the dimensionalities are the same. All transformers are expected to work with aliased inputs and output.

### isInverse

`public abstract boolean isInverse(Transformer trans)`
Are these two transformations, inverses of each other? This method is used to optimize a series of transformations where transformations.

### transform

```public void transform(double[][] in,
double[][] out)```
Convert an array of points where the output vectors are supplied. The vectors should have dimensionality [2][n] or [3][n]. The first dimension gives the index within the vector while the second gives which vector is being processed. This means that the user needs to create only a few objects (3 or 4) rather than of order n objects for each array. In practice this seems to speed up code by a factor of 4. (JDK1.5).

Parameters:
`in` - A set of positions to be transformed. The first dimension should be consistent with getInputDimension, while the second is the number of points to be transferred.
`out` - The updated positions. The first dimension should be consistent with getOutputDimension, while the second is the number of points to be transferred. This argument may point to the same data as the input.