Numeric Calculation

Description

This part allows application users to enter a mathematical expression so the system can perform a calculation.

Use

The calculation part is used by entering the requested mathematical expression in the part. The system stores the calculated result in the defined data object. This part is recommended for any formula-based math., especially when working with integers. It will correctly handle decimals but does not have built-in rounding. Two alternatives are to use a format variable part on the result, or to use a calculation to round to the required number of decimals (see Tips below).

The advanced calculation part has all the same functionality below but also

1. works with "large numbers" (> 16 digits) as well as more common numbers with fewer digits
2. has a parameter for rounding (such that you just specify the number of decimal places). The article for this part can be found here.

Editor Fields

Mathematical expressions can include the following elements: 

• numbers (whole and floating using ‘.’ as decimal point)
• standard operators, such as  +, -, /, *, ^ 
• parentheses to control the precedence of the operators
• mathematical functions: sqrt, abs, ceil, floor, log, log10, max, min, mod, cos, acos, sin, asin, tan

The function max returns the maximum value of its numeric arguments, and  the min function computes the minimum value. Both can be used with an unlimited number of arguments.

The function mod is equivalent to the % operator.

For trigonometric functions, angles are expressed in degrees.
 

Using Data Variables from the Model

Mathematical expressions can also include interpolated text , such as $(my_var).

In support of interpolation, a default value can be defined in case the variable itself has not yet been defined by the runtime logicnets. Default values should be used in most scenarios to prevent a calculation error or warning message during runtime.

Default Values

Default values are specified inside the () and after a colon as follows.

$(my_var:0) gives a result of 0 if my_var is NULL
$(my_var:1) gives a result of 1 if my_var is NULL
 

Sample Mathematical Expressions

sqrt(100)       ==> 10

(4 – 8) * 3     ==> -12

abs(4-8)*3      ==> 12

ceil (2.6)      ==> 3

floor (2.6)     ==> 2

log(100)        ==> 4.6051

log10(100)      ==> 2

max(14, 2, 100) ==> 100

min(14, 2, 100) ==> 2

sin(90)         ==> 1

asin(1)         ==> 90

cos(90)         ==> 6.123233995736766e-017

acos(0)         ==> 90

tan(45)         ==> 0.9999999999999999

Tips & Tricks

If you are using this part, but need to round a number to a given number of decimals mid-stream, it may not be appropriate to switch to the advanced calculation process node to access the rounding parameter. Instead you can use a mathematical expression to round.

ROUNDED to r places = floor ( [your-variable] * 10^{^}r + 0.5) / 10^{^}r 

• Example:  3.14159 rounded = floor (3.14159 x 100 +0.5) / 100  = floor (314.5556) / 100 = 314 / 100 = 3.14
• Example: 8/3 rounded to 1 decimal place  = floor (2.666666r * 10 + 0.5) / 10 = floor (27.166666.r ) / 10 = 27 / 10 = 2.7

In other words, we multiply then add 0.5 to round up, use floor to remove the excess digits beyond the number we want, and then divide to get back to the order of magnitude we started with.

Example

For an example form  in which you can enter a mathematical expression the system will pass to the calculation part, download and import the following sample project in your workspace.