perform

Calculate network performance

Syntax

perform(net,t,y,ew)


Description

perform(net,t,y,ew) takes these arguments,

net	Neural network
t	Target data
y	Output data
ew	Error weights (default = {1})

and returns network performance calculated according to the net.performFcn and net.performParam property values.

The target and output data must have the same dimensions. The error weights may be the same dimensions as the targets, in the most general case, but may also have any of its dimensions be 1. This gives the flexibility of defining error weights across any dimension desired.

Error weights can be defined by sample, output element, time step, or network output:

ew = [1.0 0.5 0.7 0.2]; % Across 4 samples
ew = [0.1; 0.5; 1.0]; % Across 3 elements
ew = {0.1 0.2 0.3 0.5 1.0}; % Across 5 timesteps
ew = {1.0; 0.5}; % Across 2 outputs

The error weights can also be defined across any combination, such as across two time-series (i.e., two samples) over four timesteps.

ew = {[0.5 0.4],[0.3 0.5],[1.0 1.0],[0.7 0.5]};

In the general case, error weights may have exactly the same dimensions as targets, in which case each target value will have an associated error weight.

The default error weight treats all errors the same.

ew = {1}

Examples

Here a simple fitting problem is solved with a feed-forward network and its performance calculated.

[x,t] = simplefit_dataset;
net = feedforwardnet(20);
net = train(net,x,t);
y = net(x);
perf = perform(net,t,y)

perf =

   2.3654e-06