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The seq() Command

Command Summary Command Syntax Calculator Compatibility Token Size
Creates a list by evaluating a formula over a range of values. seq(formula,variable,start,end[,step-size] This command works on all calculators. 2 bytes
  • Press 2nd MATH to enter the MATH popup menu.
  • Press 3 to enter the List submenu.
  • Press 1 to select seq(.

The seq() Command

The seq() command creates a list of terms of a sequence: seq(formula,variable,start,end) evaluates formula for every value of variable from start to end. Optionally, a fifth argument, step-size, is included: this increases the value of variable by step-size for each element, instead of 1.

seq() is similar to a 68k:For..EndFor loop, but instead of repeating a block of commands every time, it only evaluates a formula.

:seq(f(x),x,1,5)
           {f(1)  f(2)  f(3)  f(4)  f(5)}
:seq(x,x,3,9,2)
           {3  5  7  9}
:seq(x^2,x,5,1,-1)
           {25  16  9  4  1}

The variable used in seq(), x in the examples, is not actually modified.

Advanced Uses

Because a matrix is just a list of lists, you can use seq() to create matrices as well as lists. The simplest way to do it is to make the formula a list:

:seq({x,2x,3x},x,1,4)
           [1  2  3 ]
           [2  4  6 ]
           [3  6  9 ]
           [4  8  12]

You can also create a matrix by nesting a seq() command inside another seq() command:
:seq(seq(row+col,col,1,4),row,1,3)
           [2  3  4  5]
           [3  4  5  6]
           [4  5  6  7]

Optimization

If all you need to do in a loop is create a list, it's probably better to use seq() than 68k:For..EndFor.

You can often use 68k:newList() instead of seq() to create an expression that gets evaluated much faster (see 68k:list-optimization for details).

Error Conditions

For the non-generic errors that might occur when using this command (that is, syntax-type errors shouldn't be included). In a format similar to the following:

260 - Domain error happens when the step-size argument is 0.
510 - Invalid list or matrix happens when the formula of seq() is a matrix, or a list that varies in size.

Authors: KG