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## org.encog.engine.network.activation
Class ActivationGaussian

    java.lang.Object
      org.encog.engine.network.activation.ActivationGaussian

All Implemented Interfaces:
  Serializable, Cloneable, ActivationFunction

    public class ActivationGaussian

extends Object
implements ActivationFunction

An activation function based on the gaussian function.

Author:
  jheaton
See Also:
  Serialized Form

Field Summary
`static int` | `PARAM_GAUSSIAN_CENTER` The offset to the parameter that holds the width.
`static int` | `PARAM_GAUSSIAN_PEAK` The offset to the parameter that holds the peak.
`static int` | `PARAM_GAUSSIAN_WIDTH` The offset to the parameter that holds the width.

Constructor Summary
`ActivationGaussian()`
`ActivationGaussian(double center, double peak, double width)` Create a gaussian activation function.

Method Summary
`void` | `activationFunction(double[] x, int start, int size)` Implements the activation function.
`ActivationFunction` | `clone()`
`double` | `derivativeFunction(double b, double a)` Calculate the derivative.
`double` | `getCenter()`
`String[]` | `getParamNames()`
`double[]` | `getParams()`
`double` | `getWidth()`
`boolean` | `hasDerivative()`
`void` | `setParam(int index, double value)` Set one of the params for this activation function.

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

Field Detail

### PARAM_GAUSSIAN_CENTER

    public static final int PARAM_GAUSSIAN_CENTER

  The offset to the parameter that holds the width.

  See Also:
    Constant Field Values

### PARAM_GAUSSIAN_PEAK

    public static final int PARAM_GAUSSIAN_PEAK

  The offset to the parameter that holds the peak.

  See Also:
    Constant Field Values

### PARAM_GAUSSIAN_WIDTH

    public static final int PARAM_GAUSSIAN_WIDTH

  The offset to the parameter that holds the width.

  See Also:
    Constant Field Values

Constructor Detail

### ActivationGaussian

    public ActivationGaussian(double center,
                              double peak,
                              double width)

  Create a gaussian activation function.

  Parameters:
    `center` - The center of the curve.
    `peak` - The peak of the curve.
    `width` - The width of the curve.

### ActivationGaussian

    public ActivationGaussian()

Method Detail

### clone

    public final ActivationFunction clone()

  Specified by:
    `clone` in interface `ActivationFunction`
  Overrides:
    `clone` in class `Object`
  Returns:
    The object cloned.

### getWidth

    public final double getWidth()

  Returns:
    The width of the function.

### getCenter

    public final double getCenter()

  Returns:
    The center of the function.

### hasDerivative

    public final boolean hasDerivative()

  Specified by:
    `hasDerivative` in interface `ActivationFunction`
  Returns:
    Return true, gaussian has a derivative.

### activationFunction

    public final void activationFunction(double[] x,
                                         int start,
                                         int size)

  Implements the activation function. The array is modified according to the activation function being used. See the class description for more specific information on this type of activation function.

  Specified by:
    `activationFunction` in interface `ActivationFunction`
  Parameters:
    `x` - The input array to the activation function.
    `start` - The starting index.
    `size` - The number of values to calculate.

### derivativeFunction

    public final double derivativeFunction(double b,
                                           double a)

  Calculate the derivative. For performance reasons two numbers are provided. First, the value "b" is simply the number that we would like to calculate the derivative of. Second, the value "a", which is the value returned by the activation function, when presented with "b". We use two values because some of the most common activation functions make use of the result of the activation function. It is bad for performance to calculate this value twice. Yet, not all derivatives are calculated this way. By providing both the value before the activation function is applied ("b"), and after the activation function is applied("a"), the class can be constructed to use whichever value will be the most efficient.

  Specified by:
    `derivativeFunction` in interface `ActivationFunction`
  Parameters:
    `b` - The number to calculate the derivative of, the number "before" the activation function was applied.
    `a` - The number "after" an activation function has been applied.
  Returns:
    The derivative.

### getParamNames

    public final String[] getParamNames()

  Specified by:
    `getParamNames` in interface `ActivationFunction`
  Returns:
    The names of the parameters.

### getParams

    public final double[] getParams()

  Specified by:
    `getParams` in interface `ActivationFunction`
  Returns:
    The params for this activation function.

### setParam

    public final void setParam(int index,
                               double value)

  Set one of the params for this activation function.

  Specified by:
    `setParam` in interface `ActivationFunction`
  Parameters:
    `index` - The index of the param to set.
    `value` - The value to set.

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