GNU octave instead matlab newff function

In GNU Octave, the newff function does not exist as it is a function specific to the Neural Network Toolbox in MATLAB. However, Octave does have its own neural network package called the Octave Neural Network Toolbox (ONNT) which provides similar functionality.

To create a new feedforward neural network in ONNT, you can use the nnet constructor function. For example, to create a network with 2 input nodes, 3 hidden nodes, and 1 output node, you can use the following code:

net = nnet([2 3 1]);

This will create a neural network object with the specified architecture. You can then train the network using the train function and predict outputs using the sim function, similar to how you would use the corresponding functions in MATLAB's Neural Network Toolbox.

Note that the syntax and functionality of ONNT may differ from that of the Neural Network Toolbox in MATLAB. It is recommended to consult the ONNT documentation for more information on how to use the package.