# adapt

Adapt neural network to data as it is simulated

## Syntax

`[net,Y,E,Pf,Af,tr] = adapt(net,P,T,Pi,Ai)`

## To Get Help

Type `help network/adapt`

.

## Description

This function calculates network outputs and errors after each presentation of an input.

`[net,Y,E,Pf,Af,tr] = adapt(net,P,T,Pi,Ai)`

takes

`net` | Network |

`P` | Network inputs |

`T` | Network targets (default = zeros) |

`Pi` | Initial input delay conditions (default = zeros) |

`Ai` | Initial layer delay conditions (default = zeros) |

and returns the following after applying the adapt function `net.adaptFcn`

with the adaption parameters `net.adaptParam`

:

`net` | Updated network |

`Y` | Network outputs |

`E` | Network errors |

`Pf` | Final input delay conditions |

`Af` | Final layer delay conditions |

`tr` | Training record ( |

Note that `T`

is optional and is only needed for networks that require
targets. `Pi`

and `Pf`

are also optional and only need to be
used for networks that have input or layer delays.

`adapt`

’s signal arguments can have two formats: cell array or
matrix.

The cell array format is easiest to describe. It is most convenient for networks with multiple inputs and outputs, and allows sequences of inputs to be presented,

`P` |
| Each element |

`T` |
| Each element |

`Pi` |
| Each element |

`Ai` |
| Each element |

`Y` |
| Each element |

`E` |
| Each element |

`Pf` |
| Each element |

`Af` |
| Each element |

where

`Ni ` | `=` | `net.numInputs` |

`Nl ` | `=` | `net.numLayers` |

`No ` | `=` | `net.numOutputs` |

`ID ` | `=` | `net.numInputDelays` |

`LD ` | `=` | `net.numLayerDelays` |

`TS ` | `=` | Number of time steps |

`Q ` | `=` | Batch size |

`Ri ` | `=` | `net.inputs{i}.size` |

`Si ` | `=` | `net.layers{i}.size` |

`Ui ` | `=` | `net.outputs{i}.size` |

The columns of `Pi`

, `Pf`

, `Ai`

, and
`Af`

are ordered from oldest delay condition to most recent:

`Pi{i,k} ` | `=` | Input |

`Pf{i,k} ` | `=` | Input |

`Ai{i,k} ` | `=` | Layer output |

`Af{i,k} ` | `=` | Layer output |

The matrix format can be used if only one time step is to be simulated (```
TS =
1
```

). It is convenient for networks with only one input and output, but can be used
with networks that have more.

Each matrix argument is found by storing the elements of the corresponding cell array argument in a single matrix:

`P` | ( |

`T` | ( |

`Pi` | ( |

`Ai` | ( |

`Y` | ( |

`E` | ( |

`Pf` | ( |

`Af` | ( |

## Examples

Here two sequences of 12 steps (where `T1`

is known to depend on
`P1`

) are used to define the operation of a filter.

p1 = {-1 0 1 0 1 1 -1 0 -1 1 0 1}; t1 = {-1 -1 1 1 1 2 0 -1 -1 0 1 1};

Here `linearlayer`

is used to create a layer with an input
range of `[-1 1]`

, one neuron, input delays of 0 and 1, and a learning rate of
0.1. The linear layer is then simulated.

`net = ``linearlayer`

([0 1],0.1);

Here the network adapts for one pass through the sequence.

The network’s mean squared error is displayed. (Because this is the first call to
`adapt`

, the default `Pi`

is used.)

[net,y,e,pf] = adapt(net,p1,t1); mse(e)

Note that the errors are quite large. Here the network adapts to another 12 time steps
(using the previous `Pf`

as the new initial delay conditions).

p2 = {1 -1 -1 1 1 -1 0 0 0 1 -1 -1}; t2 = {2 0 -2 0 2 0 -1 0 0 1 0 -1}; [net,y,e,pf] = adapt(net,p2,t2,pf); mse(e)

Here the network adapts for 100 passes through the entire sequence.

p3 = [p1 p2]; t3 = [t1 t2]; for i = 1:100 [net,y,e] = adapt(net,p3,t3); end mse(e)

The error after 100 passes through the sequence is very small. The network has adapted to the relationship between the input and target signals.

## Algorithms

`adapt`

calls the function indicated by `net.adaptFcn`

,
using the adaption parameter values indicated by `net.adaptParam`

.

Given an input sequence with `TS`

steps, the network is updated as
follows: Each step in the sequence of inputs is presented to the network one at a time. The
network’s weight and bias values are updated after each step, before the next step in the
sequence is presented. Thus the network is updated `TS`

times.

## Version History

**Introduced before R2006a**