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Creates a list by evaluating a formula over a range of values.
seq(formula,variable,start,end[,step-size]
Menu Location
- Press 2nd MATH to enter the MATH popup menu.
- Press 3 to enter the List submenu.
- Press 1 to select seq(.
This command works on all calculators.
2 bytes
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 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 For..EndFor.
You can often use newList() instead of seq() to create an expression that gets evaluated much faster (see 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.