- Prolog - Home
- Prolog - Introduction
- Prolog - Environment Setup
- Prolog - Hello World
- Prolog - Basics
- Prolog - Relations
- Prolog - Data Objects
- Loop & Decision Making
- Conjunctions & Disjunctions
Prolog Operators
- Prolog - Type of Operators
- Prolog - Arithmetic Comparison Operators
- Prolog - Unification Operators
- Prolog - Term Comparision Operators
- Prolog - Arithmetic Operators
- Prolog - Logical Operators
- Prolog - List Operators
- Prolog - Custom Operators
Prolog Lists
- Prolog - Lists
- Prolog - Member of List
- Prolog - Length of List
- Prolog - Concatenating Lists
- Prolog - Appending to a List
- Prolog - Deleting from a List
- Prolog - Inserting into a List
- Prolog - Permutation Operation
- Prolog - Combination Operation
- Prolog - Reverse Items of a List
- Prolog - Shift Items of a List
- Prolog - Check Order of a List
- Prolog - SubSet of a Set
- Prolog - Union of Sets
- Prolog - Intersection of Sets
- Prolog - Even and Odd Length Finding
- Prolog - Divide a List
- Prolog - Find Maximum of a List
- Prolog - Find Minimum of a List
- Prolog - Find Sum of a List
- Prolog - Sorting List using MergeSort
Built-In Predicates
- Prolog - Built-In Predicates
- Prolog - Identifying Terms
- Prolog - Decomposing Structures
- Prolog - Collecting All
- Prolog - Mathematical Predicates
- Prolog - Scientific Predicates
Miscellaneous
- Recursion and Structures
- Prolog - Backtracking
- Prolog - Preventing Backtracking
- Prolog - Different and Not
- Prolog - Inputs and Outputs
- Tree Data Structure (Case Study)
- Prolog - Examples
- Prolog - Basic Programs
- Prolog - Practical Arithmetic Examples
- Prolog - Examples of Cuts
- Towers of Hanoi Problem
- Prolog - Linked Lists
- Monkey and Banana Problem
- Prolog Useful Resources
- Prolog - Quick Guide
- Prolog - Useful Resources
- Prolog - Discussion
Prolog - Airthmetic Operators
Airthmetic Operators are for various arithmetic operations in Prolog. Following is the list of arithmetic operators −
| Operator | Meaning | Example Usage | Result |
|---|---|---|---|
| + | Returns the sum of two numbers. | X is 5 + 2. | X = 7 |
| - | Returns the subtraction of two numbers. Can act as unary minus as well. | X is 5 - 2. | X = 3 |
| * | Returns the multiplication of the numbers. | X is 5 * 2. | X = 10 |
| / | Returns the division of the numbers | X is 5 / 2. | X = 2.5 |
| // | Used for integer division. | X is 5 // 2. | X = 2 |
| mod | Used for modulo operation. | X is 5 mod 2. | X = 1 |
| ^ or ** | Used for exponentiation. | X is 5 ** 2. | X = 25.0 |
| abs/1 | Used to get absolute value. | X is abs(-2). | X = 2 |
| sqrt/1 | Used to get square root value. | X is sqrt(9). | X = 3.0 |
| float/1 | Used to convert number to float. | X is float(9). | X = 9.0 |
| round/1 | Used to round number to nearest integer. | X is round(9.3). | X = 9 |
| truncate/1 | Used to truncate number to integer. | X is truncate(9.3). | X = 9 |
| float_fractional_part/1 | Used to get fractional part of a float. | X is float_fractional_part(3.14) | X = 0.14000000000000012 |
| float_integer_part/1 | Used to get integer part of a float. | X = 3.0 | |
| min/2 | Used to get minimum of two numbers. | X is min(3,5) | X = 3 |
| max/2 | Used to get maximum of two numbers. | X is max(3,5) | X = 5 |
| pi | Used to get constant value of pi. | X is pi. | X = 3.1415926535897931 |
| is | Used to evaluate the arithmetic expression and unifies the result. | X is 5 + 2. | X = 7 |
is/2 predicate
is operator is used to evaluate the arithmetic expression and in Prolog, arithmetic expressions are not automatically evaluated.
Example
| ?- X is 5 + 2. X = 7 yes | ?- Y is 20/5. Y = 4.0 yes | ?- Z is (3 + 5) * 2. Z = 16 yes | ?-
If a variable is present in the arithmetic expression then it should be instantiated to a number before being evaluated using is operator otherwise prolog will report error.
| ?- A is B + 2. uncaught exception: error(instantiation_error,(is)/2)
Divison by default returns a float. In case of integer based division, we can use // operator as shown below −
| ?- C is 20//5. C = 4 yes | ?-
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