tessl/npm-thi-ng--math

Assorted common math functions & utilities for TypeScript/JavaScript applications

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LibC Math Functions

Name: tessl/npm-thi-ng--math
Author: tessl

C standard library math functions providing low-level mathematical operations for compatibility with C and enhanced precision control.

Capabilities

Sign and Magnitude Operations

Functions for manipulating the sign and magnitude components of floating-point numbers.

/**
 * Returns a value with the magnitude of x and the sign of y
 * @param x - Source magnitude 
 * @param y - Source sign
 * @returns Value with magnitude of x and sign of y
 */
function copysign(x: number, y: number): number;

Exponential Functions

Power functions using base 2 operations.

/**
 * Returns 2^x
 * @param x - Exponent value  
 * @returns 2 raised to the power of x
 */
function exp2(x: number): number;

Difference and Multiplication

Functions for positive differences and fused multiply-add operations.

/**
 * Returns the positive difference between x and y, i.e. x - y if x > y, otherwise zero
 * @param x - First value
 * @param y - Second value  
 * @returns Positive difference or zero
 */
function fdim(x: number, y: number): number;

/**
 * Fused multiply-add operation: returns x * y + z
 * @param x - First multiplicand
 * @param y - Second multiplicand
 * @param z - Additive term
 * @returns Result of x * y + z
 */
function fma(x: number, y: number, z: number): number;

Modulo Operations

C-style modulo operations with different behavior from JavaScript's default % operator.

/**
 * C-style modulo operation. Returns x - y * trunc(x / y)
 * Result will always have the sign of x
 * @param x - Dividend
 * @param y - Divisor
 * @returns C-style modulo result
 */
function fmod(x: number, y: number): number;

/**
 * IEEE remainder function. Returns x - y * round(x / y)
 * @param x - Dividend  
 * @param y - Divisor
 * @returns IEEE remainder
 */
function remainder(x: number, y: number): number;

Binary Decomposition

Functions for breaking down and reconstructing floating-point numbers using binary significand and exponent.

/**
 * Breaks number x into binary significand and exponent
 * Returns [significand, exponent] where x = significand * 2^exponent
 * Significand has absolute value in [0.5, 1.0) interval
 * @param x - Input number  
 * @returns Tuple of [significand, exponent]
 */
function frexp(x: number): [number, number];

/**
 * Inverse of frexp. Returns x * 2^exp  
 * @param x - Significand value
 * @param exp - Exponent value
 * @returns Reconstructed floating-point number
 */
function ldexp(x: number, exp: number): number;

Integer Division

Extended division operations returning both quotient and remainder.

/**
 * Computes both quotient and remainder of integer division x / y
 * @param x - Numerator (converted to integer)
 * @param y - Denominator (converted to integer)  
 * @returns Tuple of [quotient, remainder]
 */
function ldiv(x: number, y: number): [number, number];

Usage Examples

import { copysign, exp2, fdim, fma, fmod, remainder } from "@thi.ng/math/libc";
import { frexp, ldexp, ldiv } from "@thi.ng/math/libc";

// Sign manipulation
copysign(5, -2); // -5 (magnitude of 5, sign of -2)
copysign(-3, 4); // 3 (magnitude of 3, sign of 4)

// Power of 2 operations  
exp2(3); // 8 (2^3)
exp2(0.5); // 1.414... (2^0.5 = sqrt(2))

// Positive difference
fdim(5, 2); // 3 (5 - 2)
fdim(2, 5); // 0 (cannot be negative)

// Fused multiply-add
fma(2, 3, 4); // 10 (2 * 3 + 4)

// C-style vs IEEE modulo
fmod(-7, 3); // -1 (sign of dividend)
remainder(-7, 3); // 2 (IEEE remainder)

// Binary decomposition and reconstruction
const [sig, exp] = frexp(12); // [0.75, 4] since 12 = 0.75 * 2^4
ldexp(0.75, 4); // 12 (reconstructed)

// Integer division with remainder
ldiv(17, 5); // [3, 2] since 17 = 3 * 5 + 2

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