PHP Predefined Mathematical Constants

PHP provides a comprehensive set of predefined mathematical constants that are essential for mathematical calculations. These constants are globally available and provide precise values for common mathematical operations.

Core Mathematical Constants

The most commonly used mathematical constants include pi, Euler's number, and their derivatives ?

<?php
    echo "Pi (M_PI): " . M_PI . "<br>";
    echo "Euler's number (M_E): " . M_E . "<br>";
    echo "Pi/2 (M_PI_2): " . M_PI_2 . "<br>";
    echo "Pi/4 (M_PI_4): " . M_PI_4 . "<br>";
    echo "Square root of 2 (M_SQRT2): " . M_SQRT2 . "<br>";
?>

Pi (M_PI): 3.1415926535898
Euler's number (M_E): 2.718281828459
Pi/2 (M_PI_2): 1.5707963267949
Pi/4 (M_PI_4): 0.78539816339745
Square root of 2 (M_SQRT2): 1.4142135623731

Logarithmic Constants

PHP provides various logarithmic constants for different bases ?

<?php
    echo "log2(e) - M_LOG2E: " . M_LOG2E . "<br>";
    echo "log10(e) - M_LOG10E: " . M_LOG10E . "<br>";
    echo "ln(2) - M_LN2: " . M_LN2 . "<br>";
    echo "ln(10) - M_LN10: " . M_LN10 . "<br>";
    echo "ln(pi) - M_LNPI: " . M_LNPI . "<br>";
?>

log2(e) - M_LOG2E: 1.4426950408889
log10(e) - M_LOG10E: 0.43429448190325
ln(2) - M_LN2: 0.69314718055995
ln(10) - M_LN10: 2.3025850929940
ln(pi) - M_LNPI: 1.1447298858494

Rounding Constants

PHP includes constants for controlling rounding behavior ?

<?php
    $value = 2.5;
    
    echo "Original value: $value<br>";
    echo "Round half up: " . round($value, 0, PHP_ROUND_HALF_UP) . "<br>";
    echo "Round half down: " . round($value, 0, PHP_ROUND_HALF_DOWN) . "<br>";
    echo "Round half even: " . round($value, 0, PHP_ROUND_HALF_EVEN) . "<br>";
    echo "Round half odd: " . round($value, 0, PHP_ROUND_HALF_ODD) . "<br>";
?>

Original value: 2.5
Round half up: 3
Round half down: 2
Round half even: 2
Round half odd: 3

Special Constants

PHP provides constants for special mathematical values ?

<?php
    echo "Not a Number (NAN): " . NAN . "<br>";
    echo "Infinity (INF): " . INF . "<br>";
    echo "Euler constant (M_EULER): " . M_EULER . "<br>";
    
    // Check if value is NaN or infinite
    echo "Is NAN a number? " . (is_nan(NAN) ? "No" : "Yes") . "<br>";
    echo "Is INF finite? " . (is_finite(INF) ? "Yes" : "No") . "<br>";
?>

Not a Number (NAN): NAN
Infinity (INF): INF
Euler constant (M_EULER): 0.57721566490153
Is NAN a number? No
Is INF finite? No

Complete Reference Table

Conclusion

PHP's predefined mathematical constants provide accurate values for complex calculations. These constants are essential for trigonometry, logarithms, and precise mathematical operations in scientific applications.