Performing a calculation

You can reach the Use calculator view by clicking on the second tab above the workspace (to the right of the My Calculators area). You will only be able to reach the Use calculator view if the currently selected calculator is ready to be used. To be ready for use, all of the following conditions must be satisfied:

1. There must be at least one Calculator block added to the calculator

2. Each calculator block must have at least one connection

3. There must be a single calculator block which can be identified as the first block. That is, it should have no connection arrows pointing towards it; only away from it.

Using a calculator

In the Use calculator view, each Calculator block is represented by a panel. The panels are positioned according to the order in which the calculations will be performed, with the first calculator being displayed at the top-left of the view.

Most Calculator blocks have parameters which are initially set at default values. The panel shown above has six parameters relating to Voice over IP calculations. The parameters are represented by either edit boxes, or drop down selection boxes.

For more information on the purpose and limits of a parameter, select the parameter using the mouse and press the F1 key.

In this case, the bandwidth calculations are affected by the level of voice activity, the voice compression scheme used, the packet interval, the characteristics of the transport and control protocols and the data link protocol. You can either leave the parameters at their default, or change them to customised values.

The final edit box is grey, and is where the block's result is displayed when the calculation has been performed.

Entering an input value

The input value to the calculator is entered in the edit box to the right of the large Calculate button, above the panels. Enter a value into this box. This value will be used as the input for the first Calculator block's calculation. The unit for this entry is shown to the right of the text entry area.

Starting the calculations

Once valid entries have been made for the input and the calculator blocks' parameters, the calculation can be initiated in one of the following ways:

Pressing the large calculate button above the panels.

Pressing F5.

Pressing the Return key while the cursor is in any of edit or drop down list boxes.

Viewing the results

Each calculator block has operational limits, and if one of these is exceeded, then an error message will appear. Assuming that all calculations were within limits, the result of each calculator block is displayed in the grey result boxes at the bottom of the panels. Bear in mind that there is not necessarily a single result to a calculation. Depending upon how the calculator was designed, there can be several outputs.