Table of Contents

• 1. Description
• 2. Syntax
  • 2.1. Stack Effect
• 3. Parameters
• 4. Return Values
• 5. Examples
  • 5.1. Basic Exponentiation
  • 5.2. Domain Restrictions
• 6. Related Commands
• 7. PostScript Level
• 8. Error Conditions
• 9. See Also

Raises a base to a power (exponentiation).

1. Description

The exp operator pops two numbers from the operand stack (base and exponent) and pushes base raised to the exponent power. If the exponent has a fractional part, the result is meaningful only if the base is non-negative. The result is always a real number.

This is a Level 1 operator, available in all PostScript implementations.

2. Syntax

base exponent exp real

2.1. Stack Effect

Table 1. Before Execution

Position	Content
Top	exponent (integer or real) - The power
Top-1	base (integer or real) - The base

Table 2. After Execution

Position	Content
Top	real (real) - base^exponent (always real)

3. Parameters

base

The base number (integer or real)

exponent

The power to raise to (integer or real)

4. Return Values

real

The result of base^exponent (always a real number)

5. Examples

5.1. Basic Exponentiation

% Integer powers
2 3 exp        % → 8.0 (2³)
10 2 exp       % → 100.0 (10²)
5 0 exp        % → 1.0 (5⁰ = 1)

% Fractional powers (roots)
9 0.5 exp      % → 3.0 (√9)
8 0.333 exp    % → 2.0 (approximately ∛8)

% Negative exponents (reciprocals)
2 -1 exp       % → 0.5 (2⁻¹ = 1/2)
10 -2 exp      % → 0.01 (10⁻²)

5.2. Domain Restrictions

% Negative base with integer exponent
-2 3 exp       % → -8.0 (valid)
-2 2 exp       % → 4.0 (valid)

% WRONG: Negative base with fractional exponent
-9 0.5 exp     % ERROR: undefinedresult

6. Related Commands

• sqrt - Square root

• ln - Natural logarithm

• log - Base-10 logarithm

• mul - Multiplication

7. PostScript Level

Available in: PostScript Level 1 and higher

8. Error Conditions

stackunderflow

The operand stack contains fewer than two elements.

typecheck

One or both operands are not numbers.

undefinedresult

Negative base with fractional exponent, or result out of range.

-4 0.5 exp     % ERROR: undefinedresult

9. See Also

• Arithmetic and Math - All arithmetic operators