# Calculates the delta functions using backpropagation

### Description

function that calculates the delta function of a darch object with batch normalization

### Usage

1 2 | ```
backpropagate_delta_bn(darch, trainData, targetData,
errorFunc = meanSquareErr, with_BN = TRUE)
``` |

### Arguments

`darch` |
a darch instance |

`trainData` |
training input |

`targetData` |
training target |

`errorFunc` |
error function to minimize during training. Right now mean squared erros and cross entropy errors are supported. |

`with_BN` |
traing with batch normalization on or off |

### References

Batch Normalization: Accelerating Deep Network Training by Reducing Internal Covariate Shift Sergey Ioffe, Christian Szegedy