Neural Network

This repository contains a simple, fully connected, dense, deep neural network, implemented in modern Fortran and parallelised using coarrays.

The implementation is highly object oriented for ease of reuse and extension.

Usage

A neural network can be constructed using

use mod_neural_network
class(neural_network), allocatable :: nn

nn = neural_network(number of inputs,
                    numbers of neurons per layer (including output layer),
                    activation function in hidden layers - e.g. relu() or sigmoid(),
                    activation function in output layer (optional),
                    L2 regularisation parameter (optional))

Example: A neural network with

• 2 inputs
• 3 hidden layers with RELU activation functions and 30, 20 and 10 neurons
• 1 output using a sigmoid function in the output layer (e.g. for binary classification)
• L2 regularisation parameter 0.01

can be constructed with

nn = neural_network(2, [30, 20, 10, 1], relu(), sigmoid(), 0.01d0)

and trained with a learning rate of 0.001 for 100 epochs with a batch size of 32 with

call nn%train(X, Y, 0.001d0, 100, 32)

where X has dimension 2 x N and Y has dimension 1 x N (where N is the number of training samples). Note that Y has to be a matrix even though the network only gives one output per input.

Compilation and installation

Prerequisites:

• gfortran, tested with 8.2. It seems no other compilers support co_sum yet.
• cmake.

Compilation sequence is the usual,

git clone https://github.com/anjohan/neuralnetwork.git
cd neuralnetwork
mkdir build
cd build
cmake .. # or FC=caf cmake ..
make

This (hopefully) gives the library libneuralnetwork.a

For parallel execution, OpenCoarrays is required. Run FC=caf cmake .. if the caf wrapper is in your PATH. If the compiler does not contain caf, -fcoarray=single is used for serial execution.