EQUATRAN Logo
EQUATRAN Logo

EQUATRAN Tutorial 1: Basic Equation Entry and Solving

In this first tutorial we will show how to enter a simple equation into EQUATRAN and obtain a solution. We will use the Antoine equation which relates the vapour pressure of a pure substance to temperature. The equation is:

log10 P = A - B / (T + C)

A, B and C are constants. The vapour pressure P can be calculated for a given temperature T, or the reverse calculation can find T for a given P.

This particular equation is trivial and can easily be rearranged to give either ‘P =’ or ‘T =’ on the left hand side. However in EQUATRAN there is no need to rearrange the equation. This becomes a great advantage when more complex equations or large numbers of equations are to be solved and a direct solution is difficult or impossible.

After installing EQUATRAN, start by running EQUATRAN either from the Windows Start menu or from the desktop icon. This window will open:

New EQUATRAN Problem
New EQUATRAN Problem

A new problem can be started by clicking File / New / Source Text on the menu. This opens a Source Text window. File / Save As can be used to give the new problem file a name with the file extension ‘.eqs’.

New Source Text
New Source Text

Now enter the equation, the values of constants A, B and C, and the value of T for which P is to be found.

Some points to note:

Tutorial 1 Input
Tutorial 1 Input

To solve the equation, click the Run (Run Button) button.

The equation is solved and the output is displayed as below. We can see the calculated value of P is 126.4.

Tutorial 1 Output
Tutorial 1 Output

Finally we can reverse the direction of the calculation without any need to rearrange the equation. Replace the last line of code to specify P instead of T and run again. This time the value of T is calculated.

Tutorial 1 Reversed
Tutorial 1 Reversed

Next: Tutorial 2 - Simultaneous Equations