# let¶

## Purpose¶

Creates a matrix from a list of numeric or character values. The result is always of type matrix, string, or string array.

## Format¶

let x = constant_list;

## Examples¶

let x;

assigns x to be:

x = 0
let x = { 1 2 3, 4 5 6, 7 8 9 };

assigns x to be:

1 2 3
x = 3 4 5
6 7 8
let x[3,3] = 1 2 3 4 5 6 7 8 9;

assigns x to be:

1 2 3
x = 3 4 5
6 7 8
let x[3,3] = 1;

assigns x to be:

1 1 1
x = 1 1 1
1 1 1
let x[3,3];

assigns x to be:

0 0 0
x = 0 0 0
0 0 0
let x = dog cat;

assigns x to be:

x = DOG
CAT
let x = "dog""cat";

assigns x to be:

x = dog
cat
let string x = { "Median Income", "Country" };

assigns x to be:

x = Median Income
Country

## Remarks¶

Expressions and variable names are not allowed in the let command, expressions such as this:

let x[2, 1] = 3*a b

are illegal. To define matrices by combining matrices and expressions, use an expression containing the concatenation operators: ~ and |.

Numbers can be entered in scientific notation. The syntax is $$dE±n$$, where d is a number and n is an integer (denoting the power of 10):

let x = 1e+10 1.1e-4 4.019e+2;

Complex numbers can be entered by joining the real and imaginary parts with a sign (+ or -); there should be no spaces between the numbers and the sign. Numbers with no real part can be entered by appending an “i” to the number:

let x = 1.2+23 8.56i 3-2.1i -4.2e+6i 1.2e-4-4.5e+3i;

If curly braces are used, the let is optional.

let x = { 1 2 3, 4 5 6, 7 8 9 };
x = { 1 2 3, 4 5 6, 7 8 9 };

If indices are given, a matrix of that size will be created:

let x[2,2] = 1 2 3 4;
x = 1 2
3 4

If indices are not given, a column vector will be created:

let x = 1 2 3 4;
1
x = 2
3
4

You can create matrices with no elements, i.e., “empty matrices” . Just use a set of empty curly braces:

x = {};

Empty matrices are chiefly used as the starting point for building up a matrix, for example in a do loop. See Matrices for more information on empty matrices.

Character elements are allowed in a let statement:

let x = age pay sex;
AGE
x = PAY
SEX

Lowercase elements can be created if quotation marks are used. Note that each element must be quoted.

let x = "age" "pay" "sex";
age
x = pay
sex