Besides the main subroutines there are other subroutines that the user can use to
define input windows, compute statistics and compute the Hessian matrix.
These are ` JNSEFI`, ` JNSTAT`, ` JNHESS` and ` JNHEIG`.

Furthermore, the subroutine ` JNTDEC` is a ``test-deck'' used to test the program
on different platforms.

`SUBROUTINE JNSEFI(ILA,I1,I2,J1,J2,NO)`

Switches off (`NO`0) or on (`NO`**>**0) the updating of weights between nodes`I1`to`I2`in layer`ILA`and nodes`J1`to`J2`in layer`ILA-1`. The input layer has number 0. If`NO`=0 the weights are set to zero and if`NO`=1 the weights are reinitialized. This choice of enabling/disabling can be used for selective input fields or for training only portions of the network. Selective input fields means that a hidden node only sees a portion of the input pattern, which is not identical to using receptive fields.`SUBROUTINE JNSTAT(IS)`

Writes out information about the network on file number`MSTJN(6)`.

`IS`=1 gives a header and number of nodes in each layer (done automatically when the network is initialized).

`IS`=2 gives the switches and parameters used in common block`/JNDAT1/`and`/JNDAT2/`.

`IS`=3 writes out an approximate time factor and the effective number of weights in the net.

`IS`=4 writes out the Hessian matrix.

`IS`=5 writes out the diagonal elements of the Hessian matrix.`SUBROUTINE JNHESS`

Computes the upper diagonal of the Hessian, assuming a summed square error, for the training pattern currently stored in`OIN`and`OUT`. After`MSTJN(2)*MSTJN(9)`calls, the Hessian is normalized and the upper diagonal copied onto the lower diagonal.`SUBROUTINE JNHEIG(IGRAD)`

Diagonalizes the Hessian matrix and computes its eigenvalues. The eigenvalues of the Hessian are placed in the vector`OUT`. If`IGRAD`0 then the eigenvectors are computed and placed in the columns of the Hessian matrix (stored in the internal common block`/JNINT5/`).`JNHEIG`stops and writes out an error message if the Hessian is asymmetric, i.e. if`JNHESS`has not been presented with the full training set (no more and no less) before`JNHEIG`is called.`SUBROUTINE JNTDEC(METHOD)`

A ``test deck'' that automatically tests`JETNET 3.0`. To check whether`JETNET 3.0`is properly installed on your computer, just invoke this subroutine. It trains a feed-forward network to separate two overlapping Gaussian distributions. Which method to use is set by the switch`METHOD`.

Fri Feb 24 11:28:59 MET 1995