Gassmann's Fluid Substitution (formerly Gassmann's Equation)

Gassmann's Equation is a lightweight software application whose purpose is to help you calculate and generate graphs with seismic velocity changes with the aid of the Gassmann’s equation, which is usually employed in geophysics.

User interface

You are welcomed by a clean layout that embeds all configuration settings into a single panel. The dedicated parameters look easy to tweak but this does not mean that you don’t need to have background knowledge about the Gassmann's equation in order to understand the whole process.
There’s no support for a help manual so you need to experiment with the setup functions on your own in order to complete the plotting process.

Plotting options

Gassmann's Equation is able to automatically compute and plot data about seismic changes based on a custom set of parameters that you need to specify. Most of them are abbreviations so less experienced users may find it difficult to know their exact meaning.
You can manually input the values directly in the main window or paste each number from the clipboard. The application generates two graphs for revealing data about the seismic changes.
On the downside, Gassmann's Equation doesn’t offer support for saving options so you cannot export the calculations and graphs to a file on your computer. There’s no button included in the primary panel for helping you clear the entire working environment with a single click, so you need to manually delete each parameter.
Tests have shown that the program carries out calculations pretty quickly. It doesn’t eat up a lot of CPU and memory resources, so the overall performance of the system is not hampered.

Bottom line

All things considered, Gassmann's Equation can be used for educational purposes for computing graphs with seismic changes.