# Visualizing TensorFlow with TensorBoard

TensorBoard is a tool for visualizing graphs and various metrics for TensorFlow session runs. With a few line of additional code, TensorBoard gathers and report run statistics in a nice graphical interface. First of all a few lines are required to TensorFlow session as in below:

```writer = tf.summary.FileWriter("output", sess.graph)
writer.close()```

Before running the session, start TensorBoard using the following command. Finally run the TensorFlow session and point the browser to the TensorBoard. # Hessian matrix in Nspire

The Hessian is a matrix composed of second order partial derivatives of function. The Nspire does not provide built-in function for this, and a handy function below achieve the same purpose, although it is good for a 2 x 2 matrix. The HP Prime provided built-in function for Hessian matrix. # Doing matrix multiplication in TI Nspire and Excel

In TI Nspire, matrix multiplication can be accomplished in the Calculator page. The process is intuitive and easy with the visual templates.

Firstly use the matrix template to define one:  Then simply do multiplication after filling in the matrix elements. Doing so in Excel required the use of the MMULT() function. A little trick is needed for this function for returning answer in array format – by pressing CTRL+SHIFT+ENTER at the same time after inputting the function for the cells selected as output array.

First step, fill in the matrix with the elements into respective cells. Mark the output region to use the array function. In this example it is also a 3×3 matrix. Apply the MMULT() function on the upper left corner cell of the region selected. The trick is here, when finished typing in the function, press CTRL+SHIFT+ENTER instead of just ENTER. The answer from the function will then be populated in the selected cells, and the formula will be displayed with curly brackets enclosed, like  {=MMULT(B2:D4,F2:H4)}. # Simplex Algorithm on the Casio 9860GII

With matrix capable calculator, simplex algorithm for common maximization problem can be solved easily like in the TI-84.

The Casio 9860GII is also equipped with equivalent matrix operations to solve the same problem.    