for iPhone and iPad Touch

CalcKit lets you create your own personalized calculators.

With CalcKit you can:

- Design calculators using your own formulas and input labels
- Enter formulas with up to seven user-defined variables
- Make use of built-in trig and other math functions
- Organize your calculators into convenient groups

CalcKit has a simple, intuitive interface, and it comes with a set of example calculators to get you started. You can create an unlimited number of personal calculators. Each formula can be as simple or as complex as you need.

CalcKit is ideal for students, scientists, engineers and others who do everyday calculations and need more than a limited set of canned formulas.

Using CalcKit

Organizing Calculators

With CalcKit, you can organize your calculators into groups. You can create as many groups as you like, and a calculator can be included in any number of groups. The ‘All Calculators’ group is always present and, as you might guess, it contains every calculator that you have. CalcKit also comes with an ‘Examples’ group (that can be deleted if you wish).

To add a group, navigate to the 'Groups' screen, tap the 'Edit' button, and tap on 'Create a new group'. You then can provide a name for the group and begin adding calculators.

To add or remove calculators from an existing group, tap the 'Edit' button when viewing that group's calculator list. Note that when you remove a calculator from a group that you have defined, it does not delete the calculator. It will still be available in the ‘All Calculators’ group and any other groups in which it is a member. To actually discard a calculator, you need to delete it from the 'All Calculators' group. (It will be automatically removed from any other groups it is in.)

While in editing mode, you also can give a group a new name using the ‘Rename’ button on the upper left corner of the screen.

To remove a group, tap the red ‘minus’ circle next to the group name on the ‘Groups’ screen while in editing mode and then on the 'Delete' button that appears. (Deleting a group does not delete the calculators in that group.)

Creating and Modifying Calculators

To create a new calculator, choose a calculator group and tap the ‘Edit’ button while the list of calculators in that group is being displayed. Then select the ‘Create a new calculator’ entry that appears at the bottom of the list of calculators. You will then be able to enter a title, formula, input labels and output precision for the new calculator.

The title and input labels can be anything you like. To learn about how to enter formulas, see the relevant section below.

You can set the number of decimal places that are displayed for the calculation by dragging the screen upward while in editing mode to reveal the precision slider. You can use the slider to choose from 0 to 15 digits past the decimal point, plus an automatic setting that will display a variable number of digits after the decimal point (up to the first zero digit) and uses scientific notation for very large values. The output precision does not affect the accuracy of the calculation, only the number of digits displayed. By default, a calculator uses the automatic setting.

In addition to displaying the overall result of a calculation, CalcKit can display intermediate results for parts of the formula. The numeric result can be shown for each part of the formula that is enclosed in parentheses. To turn on this capability for a particular calculator, move the screen up while in editing mode to reveal the switch labeled 'Show subexpressions'. When this switch is on, a button will appear to the right of the result of each calculation. Tap this button to show a new window containing the intermediate results. You can place parentheses around any part of a formula that you want to see a result for, but be aware that parentheses can change the order of evaluation within an equation so they cannot be placed arbitrarily.

To modify an existing calculator, tap the 'Edit' button in the top right corner of the screen while the calculator is being displayed. After editing the calculator, tap the 'Done' button to save your changes or the 'Cancel' button to discard any changes.

About Variables and Labels

Input labels link the numeric values that you enter for each calculation to specific variables in a formula. Up to seven variables, named A through G, can be used in formulas. A variable becomes available for use in a formula when you provide a label for it while in editing mode. When you leave editing mode and are ready to use the calculator, a text box will appear for each variable that has a label, which allows you to enter a value for that variable to be used in the formula.

Creating Formulas

Formulas are mathematic expressions that incorporate the input values that you provide. You can use the + (addition), - (subtraction or negation), / (division), * (multiplication) and ^ (exponentiation) operations in your formulas, along with a set of predefined functions and mathematical constants (see below). Variables are entered into formulas as the uppercase letters A, B, C, D, E, F or G. Some examples of simple formulas are:

Convert a value in inches (provided in variable A) to centimeters: A*2.54
Convert temperature in Celsius to Fahrenheit: A*9/5+32
Find the area of a circle given the radius: pi*A*A (or pi*A^2)

The format of numbers used in formulas is specific to your particular country or region, so you should enter a period (.) or comma (,) as the decimal separator as you normally would. (Thousands separators cannot be used in formulas.)

Operator precedence

Operators have standard mathematical precedence. For instance, multiplication and division operations are evaluated before addition or subtraction. The precedence of operations, in decreasing order, is:

multiplication, division
addition, subtraction

Operations with the same precedence are evaluated left-to-right, except for exponentiation, which is evaluated right-to-left. So for instance:

4+4/2-1 = 5
2.0*-2.0 = -4.0
2^3^2 = 512
-2^2 = -4

Use parentheses to change the order of operations as necessary. For instance:

(4+4)/(2-1) = 8
(2^3)^2 = 64
(-2)^2 = 4

Available Functions and Constants

The following mathematical functions can be used in formulas. All functions take a single variable, number or mathematical expression as an input argument.

abs - absolute value
acos or arccos - arccosine (inverse cosine)
asin or arcsin - arcsine (inverse sine)
atan or arctan - arctangent (inverse tangent)
cos - cosine
cbrt - cube root
ceil or ceiling - round up to an integer
floor - round down to an integer
ln - natural logarithm
log - base 10 logarithm
round - round to nearest integer
sin - sine
sqrt - square root
tan - tangent
trunc - remove the fractional part of a number

The trigonometric functions cos, sin and tan require input arguments given in radians. The output values of the functions acos, asin, atan also are provided in radians. Two predefined constants can be used to convert between degrees and radians:

deg - multiply a value by this constant to convert radians to degrees
rad - multiply by this to convert degrees to radians

The mathematical constants e and pi are also available for use in formulas.