Arithmetic & Operators

Scalar operators

For modulo use the mod(a, b) function. % is a comment character, not a modulo operator.

Comments

% and # start line comments. Everything to the right is ignored:

% full-line comment
x = 5;   % inline comment — x is still assigned

Multi-line block comments span from %{ to %} (each on its own line):

%{
  Everything inside this block is ignored.
  The %{ and %} must be the only non-whitespace content on their line.
%}
y = 10;

A same-line form %{ text %} is also valid. Hash-style #{ … #} works identically.

Comparison operators

Return 1.0 (true) or 0.0 (false). Work element-wise on matrices.

Logical operators

See Comparison & Logical Operators for full details.

Precedence (high → low)

1. postfix ' — transpose
2. ^, .^ — right-associative
3. unary -, ~ — negation, logical NOT
4. *, /, .*, ./, .^, implicit multiplication
5. +, -
6. : — range
7. ==, ~=, <, >, <=, >= — comparison (non-associative)
8. && — logical AND
9. || — logical OR (lowest)

Use parentheses to override: (2 + 3) * 4 → 20.

Special values: Inf, NaN, and division by zero

Division by zero follows IEEE 754 — it produces Inf or NaN rather than an error:

1 / 0      % Inf
-1 / 0     % -Inf
0 / 0      % NaN
0 \ 1      % Inf  (left division: 1/0)

These values propagate through arithmetic in the expected way:

Inf + 1    % Inf
Inf - Inf  % NaN
1 / Inf    % 0
isnan(NaN) % 1
isinf(Inf) % 1

Partial expressions

An expression starting with an operator uses ans as the left operand:

[ 100 ]: / 4
[ 25 ]: ^ 2
[ 625 ]:

Implicit multiplication

A number, variable, or closing parenthesis immediately before ( multiplies:

2(3 + 1)      →   8      (same as 2 * (3 + 1))
(2 + 1)(4)    →  12
2(3)(4)       →  24

Unary minus

-5
-(3 + 2)      →  -5
--5           →   5

Unary minus has lower precedence than ^ and .^, matching MATLAB/Octave:

-3 ^ 2        →  -9    % same as -(3^2), not (-3)^2
-x .^ 2       →  -(x .^ 2)
(-3) ^ 2      →   9    % use parentheses to negate before raising

Matrix operators

When one or both operands are matrices, the same operators apply with element-wise or broadcast semantics:

See Matrices for full details.