Neural Network Toolbox

ddotprod

Dot product weight derivative function

Syntax

dZ_dP = ddotprod('p',W,P,Z)

dZ_dW = ddotprod('w',W,P,Z)

Description

ddotprod is a weight derivative function.

ddotprod('p',W,P,Z) takes three arguments,

• W - S x R weight matrix.

  P - R x Q Inputs.

  Z - S x Q weighted input.

and returns the S x R derivative dZ/dP.

ddotprod('w',W,P,Z) returns the R x Q derivative dZ/dW.

Examples

Here we define a weight W and input P for an input with three elements and a layer with two neurons.

• W = [0 -1 0.2; -1.1 1 0];
  P = [0.1; 0.6; -0.2];
  

Here we calculate the weighted input with dotprod, then calculate each derivative with ddotprod.

• Z = dotprod(W,P)
  dZ_dP = ddotprod('p',W,P,Z)
  dZ_dW = ddotprod('w',W,P,Z)
  

Algorithm

The derivative of a product of two elements with respect to one element is the other element.

• dZ/dP = W
  dZ/dW = P
  

See Also

dotprod

concur

dhardlim