---
id: java-math
title: "Java Math"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["Math class", "자바 수학"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["java", "programming", "w3schools", "math"]
raw_sources: ["https://www.w3schools.com/java/java_math.asp"]
applied_in: []
github_commit: ""
---

# [[Java Math]]

## 🎯 한 줄 통찰 (One-line insight)
`Math.pow()` always returns a `double` even for whole-number results (`Math.pow(2,8)` gives `256.0`, not `256`), and `Math.random()` always returns a `double` in `[0.0, 1.0)`, requiring an explicit `(int)` cast plus scaling formula to get a bounded random integer. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`Math.max(x,y)` / `Math.min(x,y)`** — highest/lowest of two values. [S1]
- **`Math.sqrt(x)`** — square root. [S1]
- **`Math.abs(x)`** — absolute value. [S1]
- **`Math.pow(x,y)`** — x raised to power y; ALWAYS returns double. [S1]
- **Rounding methods** — `Math.round(x)` (nearest integer), `Math.ceil(x)` (round up), `Math.floor(x)` (round down). [S1]
- **`Math.random()`** — random double in `[0.0, 1.0)`. [S1]
- **Bounded random integer formula** — `(int)(Math.random() * 101)` for 0-100. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **pow() always returns double** — even `Math.pow(2, 8)` (a clean integer result) comes back as `256.0`, not `256` — a type consistency rule worth remembering when assigning the result to a variable. [S1]
- **random-int-in-range formula** — `(int)(Math.random() * (max+1))` scales the `[0,1)` double up to the desired range and truncates via cast — the standard idiom for bounded random integers. [S1]

## 📖 세부 내용 (Details)
- Max/min: `Math.max(5, 10); Math.min(5, 10);`. [S1]
- Square root/absolute: `Math.sqrt(64); Math.abs(-4.7);`. [S1]
- Power (always double): `Math.pow(2, 8); // 256.0`. [S1]
- Rounding: `Math.round(4.6); // 5`, `Math.ceil(4.1); // 5.0`, `Math.floor(4.9); // 4.0`. [S1]
- Bounded random int: `int randomNum = (int)(Math.random() * 101); // 0 to 100`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **pow()의 반환 타입**: 결과가 정수여도 항상 double을 반환한다는 점이 소스에서 명시적으로 강조됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 0~100 사이 난수 생성 공식은 게임/시뮬레이션에서 표준적으로 쓰인다. [S1]

## 💻 코드 패턴 (Code patterns)
Bounded random integer via cast (Java):
```java
int randomNum = (int)(Math.random() * 101); // 0 to 100
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[Java Tutorial]]
- **관련 개념:** [[Java Numbers]], [[Java Type Casting]], [[Python Math]]
- **참조 맥락:** 수학 계산의 기본 도구 — pow()의 double 반환, random() 범위 지정 공식이 핵심.

## 📚 출처 (Sources)
- [S1] W3Schools — Java Math — https://www.w3schools.com/java/java_math.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "Java Math" page (Astra wiki-curation, P-Reinforce v3.1 format).