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# normprod

Normalized dot product weight function

## Syntax

Z = normprod(W,P,FP)
dim = normprod('size',S,R,FP)
dw = normprod('dz_dw',W,P,Z,FP)

## Description

normprod is a weight function. Weight functions apply weights to an input to get weighted inputs.

Z = normprod(W,P,FP) takes these inputs,

 W S-by-R weight matrix P R-by-Q matrix of Q input (column) vectors FP Row cell array of function parameters (optional, ignored)

and returns the S-by-Q matrix of normalized dot products.

dim = normprod('size',S,R,FP) takes the layer dimension S, input dimension R, and function parameters, and returns the weight size [S-by-R].

dw = normprod('dz_dw',W,P,Z,FP) returns the derivative of Z with respect to W.

## Examples

Here you define a random weight matrix W and input vector P and calculate the corresponding weighted input Z.

```W = rand(4,3);
P = rand(3,1);
Z = normprod(W,P)
```

## Network Use

You can create a standard network that uses normprod by calling newgrnn.

To change a network so an input weight uses normprod, set net.inputWeight{i,j}.weightFcn to 'normprod'. For a layer weight, set net.layerWeight{i,j}.weightFcn to 'normprod'.

In either case, call sim to simulate the network with normprod. See newgrnn for simulation examples.

```z = w*p/sum(p)