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Arithmetic

The arithmetic operators work on NUMBER. Each has a word form and a symbol form, except MODULO, which has only the word.

Word Symbol Operation Example
PLUS + addition 5 PLUS 3 is 8
MINUS - subtraction 10 - 4 is 6
TIMES * multiplication 6 TIMES 7 is 42
DIVIDED BY / division 10 / 4 is 2.5
MODULO remainder after division 17 MODULO 5 is 2

Example file:

-- Arithmetic keyword examples

-- PLUS (Addition)

#EVAL 5 PLUS 3
#EVAL 5 + 3
#EVAL 10.5 + 2.5
#EVAL (-3) + 8

-- MINUS (Subtraction)

#EVAL 10 MINUS 4
#EVAL 10 - 4
#EVAL 5 - 8
#EVAL 0 - 5

-- TIMES (Multiplication)

#EVAL 6 TIMES 7
#EVAL 6 * 7
#EVAL 3.14 * 2
#EVAL (-3) * 4

-- DIVIDED BY (Division)

#EVAL 15 DIVIDED BY 3
#EVAL 15 / 3
#EVAL 10 / 4
#EVAL 7 / 2

-- MODULO (Remainder)

#EVAL 17 MODULO 5
#EVAL 10 MODULO 3
#EVAL 8 MODULO 2

-- Operator Precedence

-- Multiplication before addition
#EVAL 2 + 3 * 4

-- Parentheses override precedence
#EVAL (2 + 3) * 4

-- Division before subtraction
#EVAL 10 - 4 / 2

-- With parentheses
#EVAL (10 - 4) / 2

-- Complex Expressions

-- Circle area: pi * r^2
GIVEN r IS A NUMBER
`area of a circle` r MEANS 3.14159 TIMES r TIMES r

#EVAL `area of a circle` 5

-- Quadratic formula discriminant: b^2 - 4ac
GIVEN a IS A NUMBER
      b IS A NUMBER
      c IS A NUMBER
discriminant a b c MEANS
  b TIMES b MINUS 4 TIMES a TIMES c

#EVAL discriminant 1 5 6

-- Practical Examples

-- Calculate tax
GIVEN price IS A NUMBER
      `tax rate` IS A NUMBER
`tax on` price `tax rate` MEANS
  price TIMES `tax rate` / 100

#EVAL `tax on` 100 8.5

-- Calculate discount
GIVEN `original price` IS A NUMBER
      `discount percent` IS A NUMBER
`discounted price` `original price` `discount percent` MEANS
  `original price` MINUS (`original price` TIMES `discount percent` / 100)

#EVAL `discounted price` 200 25

-- Combining with Comparisons

ASSUME income IS A NUMBER
ASSUME expenses IS A NUMBER

DECIDE profit IS income MINUS expenses
DECIDE `is profitable` IS profit GREATER THAN 0

#CHECK `is profitable`

Exact numbers

Arithmetic is exact: (1 / 3) * 3 = 1 and 0.1 + 0.2 = 0.3 are both TRUE. A result that has no finite decimal form, such as 1 / 3, is shown rounded (0.3333333333333333), but the value itself is exact.

MODULO works on whole numbers only: 7 MODULO 2.5 stops evaluation with an error. A negative number in an expression needs parentheses: (-3) * 4.

Precedence

TIMES, DIVIDED BY and MODULO bind more tightly than PLUS and MINUS, and operators of the same level are applied from left to right:

#EVAL 2 + 3 * 4        -- 14
#EVAL (2 + 3) * 4      -- 20
#EVAL 10 - 4 - 3       -- 3

The full table, with comparisons and logical operators, is in Operators: Precedence.

More functions

Rounding (ROUND, FLOOR, CEILING, TRUNC) and functions such as SQRT are built-in functions. The math library adds more.