Constants Library

Introduction

This library provides a collection of commonly used mathematical constants, unit-conversion macros, SI and IEC prefixes, and data-type-related constants.

The library is organized into three main categories:

• Mathematical constants and precomputed values.
• Unit conversion and measurement prefixes.
• Data type limits, ranges, and floating-point precision values.

Features

The constants library provides:

• Mathematical constants such as pi and tau.
• Precomputed powers of Euler's number.
• Precomputed square-root and cube-root values.
• Integer type minimum and maximum values.
• Floating-point range and magnitude constants.
• Floating-point machine epsilon values.
• Macros for unit conversions, such as:
  • Length, mass, and time
  • Frequency and period
  • Temperature
  • Angle
  • Rotational speed
• SI decimal prefixes.
• IEC binary prefixes.

Header Files

The library is provided through the following headers:

• constants.h - Main header that includes all constant definitions.
• constants_math.h - Mathematical constants and precomputed values.
• constants_units.h - Unit conversion macros and SI/IEC prefixes.
• constants_data_type.h - Data type range and precision constants.

Mathematical Constants

The mathematical constants header provides commonly used values of pi, tau, Euler's number, square roots, and cube roots.

Examples include:

double pi  = MATH_PI;
double tau = MATH_TAU;
double e   = MATH_e;
 
double sqrt_2 = MATH_SQRT_2;
double cbrt_2 = MATH_CUBRT_2;

Precomputed multiples and sub-multiples of pi are also available, together with powers of Euler's number and roots from 2 through 25.

Unit Conversion

The unit conversion header provides macros for commonly used engineering and scientific unit conversions.

Length

Examples:

double meters = IN_2_M(10.0);
double feet   = M_2_FT(2.0);
double miles  = M_2_MILE(1609.344);

Mass

Examples:

double kg = LB_2_KG(10.0);
double lb = KG_2_LB(5.0);

Time

Examples:

double ms = SEC_2_MS(2.0);
double s  = MS_2_SEC(500.0);

Frequency and Period

Examples:

double period = HZ_2_SEC(100.0);
double freq   = SEC_2_HZ(0.01);

Temperature

Examples:

double fahrenheit = C_2_F(25.0);
double kelvin     = C_2_K(25.0);
double celsius    = F_2_C(77.0);

Angle

Examples:

double radians = DEG_2_RAD(90.0);
double degrees = RAD_2_DEG(MATH_PI);

Rotational Speed

Examples:

double radps = RPM_2_RADPS(1000.0);
double rpm   = RADPS_2_RPM(10.0);

Prefixes

The library provides SI decimal prefixes ranging from QUETTA through QUECTO.

Examples:

double mega = MEGA;
double micro = MICRO;
double nano = NANO;

IEC binary prefixes are also provided:

auto kibi = KIBI;
auto mebi = MEBI;
auto gibi = GIBI;

Data Type Constants

The data type constants header provides minimum and maximum values for integer types together with floating-point range and precision constants.

Examples:

auto int_min = INT_32_MIN;
auto int_max = INT_32_MAX;
 
double epsilon = DOUBLE_EPSILON;
float  small   = FLOAT_SMALL;

Floating-point constants include:

• FLOAT_MIN
• FLOAT_MAX
• FLOAT_MIN_POS
• FLOAT_SMALL
• FLOAT_BIG
• FLOAT_EPSILON
• DOUBLE_MIN
• DOUBLE_MAX
• DOUBLE_MIN_POS
• DOUBLE_SMALL
• DOUBLE_BIG
• DOUBLE_EPSILON

Basic Usage

The complete constants library can be included through the main header:

#include "constants.h"
 
double angle = DEG_2_RAD(90.0);
double value = MATH_PI * 2.0;
double time  = MS_2_SEC(100.0);

Library Organization

The library is divided into the following functional groups:

• Mathematical constants: constants_math.h
• Unit conversions and prefixes: constants_units.h
• Data type constants: constants_data_type.h
• Unified library interface: constants.h

Copyright

Copyright (c) 2026 Abhinay Kumar