Custom Formulas app help
Last updated Nov 2022
Main page
On the first page of the app, you can choose a formula category and formula group using the two drop-down lists at the top.
The category is a grouping so that like formulas can be stored together e.g. financial formulas, geometry formulas, etc. To create a new category,
press the blue ">" button to the right of the category drop-down, choose "Add", and enter a name.
The formula group is specified in the second drop-down list and is labelled "Name". Often a formula group will only contain a single formula, but
you can also create a group of formulas which can be computed together. To add a formula group, click the blue ">" button to the right of the drop-down,
choose "Add", and then enter a name for the formula or group of formulas. Once you have added a new formula group, you are taken to the Formula Group page which is described below.
Note that you can also enter an optional description for the formula group from
this menu. This optional description is shown on the main page when you select the formula group and just allows you to show some additional information.
Below the two drop-downs is a green "Go" button which prompts you to enter input values for the currently selected formula group and then computes the
result. Beside the "Go" button is a menu button which gives you additional options, including to edit the global constants. Global constants include the built-in e and pi, which cannot be changed,
as well as any constants you choose to add. These constants can then be used in any formula expression.
Formula group page
This page allows you to add and edit formulas to a formula group. To add a formula, press the "Add formula" button at the bottom. Enter a formula of the form A = ..., where A is the variable
name for the result and the right-hand side of the expression is a mathematical expression which may include numbers, functions, and input variable names.
e.g KPH = MPH / 0.62137 to convert from miles-per-hour to kilometres-per-hour.
Once you have entered your formula, you can go back to the main page and press "Go". This will take you to the formula computation page where you can enter an input
value e.g. 100 for MPH, and press "Compute" to see the output value, e.g. KPH = 160.934
If you wish to make your formula computation page more readable, you can also enter a description for each input and output variable by clicking on the formula on the Formula Group page and then choosing
"Input variables" or "Output variables". Click on a variable name to bring up options to edit the description, change the order, or change the displayed numeric precision.
Backing up the app and transferring data to a new phone
To make a copy of the internal database used by the app, press the menu button on the main page and choose "About", then press the "Copy database"
button and then choose "Copy internal database".
Then, to backup the app data, plug your phone into a computer using a USB cable, and choose the USB file transfer option on your phone. Using a file browser such as Windows Explorer on your computer, copy the folder Android/data/binaryearth.customformulas to a safe place on your computer.
To restore the app data from the backup, or to transfer the data to a new phone, first make sure the Custom Formulas app is installed on the phone, then using a file browser on your computer, copy the binaryearth.customformulas folder to Android/data on your phone.
Next, run the Custom Formulas app on your phone and choose About > Copy database > Restore internal database.
Finally, if necessary, exit and re-start the app.
An open forum where you can share formulas is located here: https://groups.google.com/forum/#!forum/custom-formulas
List of supported operators and functions
A Definition of the Custom Formulas CF file format
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