Define numeric variables with functions

Updated 30 Aug 2024

You can use any of the following functions when defining the minimum and maximum fields for a numeric variable or in an answer box.

Function Format Purpose & Example
rand rand(range-start,range-end,exponent) Purpose:
Generates a random number within a specified range, optionally rounded to a specific power of 10.

Example:
rand(10,100,1) randomly returns 10, 20, 30, ...100. The default value for exponent is 0; that is, the value returned is rounded to the nearest integer.
round round(value,exponent) Purpose:
Rounds a value to a specific power of 10.

Example:
round(1.2345,-3) returns 1.235.

sigdig sigdig(value,exponent) Purpose: Rounds a value to a specific number of significant digits.

Example:
sigdig(1.2345,3) returns 1.23.
ifthenelse ifthenelse(test,true_value,false_value) Purpose:
Returns one of two values depending on the result of a logical test.

Example:
ifthenelse(x>y,x,y) returns x if x is larger; otherwise it returns y. See below for sample values.

 

The ifthenelse function returns one of two values, depending on the result of a logical test. In the example below, the ifthenelse function produces a value 0 or 1 for y, based on the value of the variable x.

  • If x is a number between 1 and 5, a value of 0 is returned for y.
  • If x is a number between 6 and 10, a value of 1 is returned for y.

Define numeric variable x

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Define numeric variable y with ifthenelse

Choose Formula or single numeric value and enter ifthenelse(x>5,1,0) in the box as a formula.

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Note: Alternatively, you could define the variable by choosing Value and entering ifthenelse(x>5,1,0) for both the minimum and maximum, with a Step value of 0. Either way, this value will display as a formula in the Define Variable form if you open the variable later for edit.

Your defined variables list would look like this. The variable "y" appears as a min, max, step value, regardless of whether you entered it as a formula or as min, max, step.

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The variables e1, e2, and e3 defined below are in an item to calculate the total energy required to convert a solid to a gas using heat capacity, heat of fusion, and heat of vaporization.

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Variable Description

e1

Function n_1*6.02 is rounded to 10-1, or to the first decimal place.

For example:
If n_1*6.02 is equal to 12.162, the value is rounded to 12.2.

e2

Function (m_1*4.184)/10 is rounded to 10-1, or to the first decimal place.

e3

Function n_1*40.7 is rounded to 100, or to the first integer.

For example:
If n_1*40.7 is equal to 12.162, the value is rounded to 12.

 

 

See also:

Define numeric variables | Display of numeric variables | Define list variables with numeric or string values | Enter variables in answers for different answer types