Quick Calculator---easy to use--evaluates a numerical expression--advanced version has units option

DMSolver---Language and algorithm for solving systems of equations--static or dynamic

BOAT3D---planing boat simulation model--uses DMSolver methodology

EDTECH---EDitor for plotting and labelling TECHnical-style graphs--also can access special DMSolver files

Flash Calculator---Vapor/Liquid equilibria & flashing of mixtures

For the version 2.5 I have changed the size and layout of the "units" window to make it easier to use. It is now 2.51. This window adjusts its height to the vertical number of pixels available, and the width needed is enlarged to 1440 pixels. V 2.01 is now 2.02; the rounding control from 2.5 has been added. Its window starts out more to the left of the screen (for small screens).

Incidentally, users installing all my programs will always get a message from Windows warning "...Do you want ... this program from an unknown publisher..." This does not mean your particular copy is infected with malware, etc. I have always practiced safe computing. To make the publisher ME I would have to get an official encrypted certificate which would be either expensive or a lot of work (or both). I have never done this.

Version 2.01 has several improvements since I published version 2.0 last fall.

My old TI-30XII electronic calculator evaluates numerical expressions, a requirement for modern calculators compared with the very old-fashioned ones that did one operation at a time. Quick Scientific Calculator works like a modern calculator, evaluating a text-line expression which may include parentheses and functions. Since there are a lot of free calculator programs around including the one which comes with Windows, mine is free also. It runs on any Windows from 2000 on up. It does not look like an electronic calculator because there are no number buttons--you can easily type numbers, and it is wide so that long expressions or long strings of numbers being added up are visible. There are trigonometric, exponential, and log functions which you click on to include them in the numerical expression text line.

This is QCalc 2.01 with a special units feature added. If the units feature is turned on, each number can optionally have a unit label attached to it within curly brackets (without a unit attached it is assumed to be dimensionless). Unit calculations occur, for example 5{m}*25{m} has the result 125{m^2}. Because of this I can include unit conversion tables in a larger window which is visible when units are turned on. There are more than 80 conversion ratios which you can click on to include them in your calculation. There are functions to click on for converting temperature scales since this conversion is not often a ratio. There are also some physical constants. QCalc2.5 is not free--see Download and licensing info

I have put together a scientific-style "QuickCalc" calculator, borrowing and modifying code from the formula compiler of EDTECH. The goal is to let the user pop up a single window and quickly evaluate numerical expressions.

I have neglected Digital Analytics applications for some time. However, now I would like to remind potential or actual users that I am still offering a limited amount of my past work online. I have recently (last winter) assisted new users by email and Zoom. I have retired from my previous teaching position and can consult on projects that are suitable for my software.

EDTECH --an application to create and edit technical-style black&white graphs & drawings -- Freely downloadable.

DMSolver--a system used to solve large systems of algebraic and or ordinary differential equations, suitable for various types of simulations with equations (simple or possibly highly complex) programmed as functions by the user -- copy protected and must be registered, but you get a 30-day free trial.

BOAT3D --a planing boat simulation model-3 degrees of freedom of motion with math based on DMSolver -- copy protected and must be registered, but you get a 30-day trial for a $300 fee.

Demo Flash Calculator -- Does chemical phase equibrium for up to 3 components-- Freely downloadable.

Non-demo Flash Calculator--for many components and can make graphical plots of several types -- copy protected and must be registered, but you get a 30-day free trial.

In 2020 I thought hard about modeling covid. Previous textbooks of infectious diseases had simple models based on something like

(Increase in infections) = Kx(Infectious people) x (Susceptible people) - (people recovering)

and so forth.

I realized that infectious people included those just becoming infectious plus those who became infectious yesterday plus those who became infectious on the day before that plus ... until time enough that they would not be infectious any more. This could be done, I thought, using the lag feature of DMSolver. But, I found that the lag feature had bugs and did not work. I developed version 6.04 whose lag feature was fixed, replacing 6.03 which has the bugs.

However, there are so many different regions (DMSolver handles regions) with different modes of infection, and for that matter, covid has evolved frequently, so I decided that any such kind of model would be pure speculation and after the lag bugs were fixed, I retired from working on any kind of new modelling.

Now I would like to reboot and get someone to use DMSolver on some kinds of manageable problems. I suspect that it could best be used in various kinds of chemical kinetics and reactor design, or simulation of specialized parts of processes. At some point in the past I learned that for typical standard distillation modelling, other commercial systems greatly outperformed the ones I had done, so traditional chemical plant flowsheet simulation has been dropped.

So I may be able soon to look for new problems to try on it and hope I can get someone else interested.

F. Dail Singleton, PhD