Defining a Range Variable

Iterative processes in Mathcad worksheets depend on range variables.

Tutorial - Defining Variables

Discussion and Example

To define a range variable:

1. Type the name of the variable followed by a colon (:), to create a definition.
2. In the placeholder, type the first number in the sequence of values.
3. Type a comma, or, if you're defining a sequence in increments of one, go to step 5.
4. Type the second number in the sequence.
5. Type a semicolon (;). Note that it appears as two dots ".."
6. In the remaining placeholder, type the last number in the sequence.

1..20	gives the range	1, 2, 3 ... 20
20..1	gives the range	20, 19, 18 ... 1
1,1.1..5	gives the range	1, 1.1, 1.2 ...5
5,3..-7	gives the range	5, 3, 1, -1 ...-7

Notes:

• If the last specified number in a defined range is not an integer multiple of the increment from the first number, the range stops short of this last value. For example, the range

  x:=0,0.1..2 · π

  has as its last value 6.2, not 2 · π. This feature can produce unexpected results when graphing periodic functions.
• If a range has units associated with it, you must specify the step size by providing a second value in the range.
• If you use a range variable as the argument to a function, as is commonly done with plots, the function is evaluated once for each value of the range variable, and returns another range variable. Such an expression does not return a vector. You must explicitly use range variables with integer values in the subscript operator to create vectors.
• Ranges cannot have more than 10⁹ (1 billion) entries.