Formula Calculator for iPhone

Index > Rules for typing math

How to type math symbols:

Formula calculator has two special keypads to type mathematics expressions. Since not all math symbols are available for display, Formula calculator uses other symbols:

* multiplication: e.g. two times four is written as 2*4
/ divide: two divided by four is written as 2/4
^ raise to a power: two raised to the power of four is written as 2^4
For multiplication you can also use dot '.' in situations when it cannot be confused with a decimal point, such as x.y. You can also use implicit multiplication such as 2x which is the same as 2*x

Other operations such as differentiation or integration are performed by functions. Information on using these functions can be found by pressing the Functions button in Formula calculator.

Scientific notation

In scientific notation, a floating point number is followed by a power of 10. For example, 5341.2 is written as 5.3412x103 . However, it is awkward to type this using a computer keyboard. Instead we use the exponent format where the power of 10 follows the symbol e or E. In this notation we would write 5.3412x103 as 5.3412e+03 or 5.3412e3. The number 0.0213 would appear as 2.13e-2

Parameter and function names

You can use any alphanumeric characters for parameters or function names, but they cannot begin with a number and the name must be unique. Formula calculator distinguishes between cases, so that F(x) is different from f(x).

Left and right assignment using the equals = symbol

The equals sign = is used to transfer the value of a calculation into a parameter name. For example myNumber=12*2 assigns the number 24 to a parameter with name myNumber. This is referred to as "right assignment" because the result of the expression is passed from right to left. That is, 24 on the right side is passed to the parameter on the left (myNumber).

Sometimes we may type an expression and then decide to assign its result to a parameter. An example is 12/6=AnotherValue. In this case the result of the calculation on the left, which is 2, is assigned to the parameter on the right (AnotherValue). This is referred to as "left assignment".

Formula calculator allows you to use either left or right assignment. It decides which one to use based on which side of the = has previously been assigned a number. If neither side evaluates to a number then Formula calculator ignores the assignment. If both sides have been previously assigned numbers, such as myNumber=AnotherValue, then Formula calculator cannot decide which parameter is to be assigned the value, and will display an error.


You can add comments into the math text using the double slash //. Everything following to the end of the line is treated as a comment and ignored.