Math Functions

    Table of Contents

    • abs — Absolute value
    • acos — Arc cosine
    • acosh — Inverse hyperbolic cosine
    • asin — Arc sine
    • asinh — Inverse hyperbolic sine
    • atan — Arc tangent
    • atan2 — Arc tangent of two variables
    • atanh — Inverse hyperbolic tangent
    • base_convert — Convert a number between arbitrary bases
    • bindec — Binary to decimal
    • ceil — Round fractions up
    • cos — Cosine
    • cosh — Hyperbolic cosine
    • decbin — Decimal to binary
    • dechex — Decimal to hexadecimal
    • decoct — Decimal to octal
    • deg2rad — Converts the number in degrees to the radian equivalent
    • exp — Calculates the exponent of e
    • expm1 — Returns exp($num) - 1, computed in a way that is accurate even when the value of number is close to zero
    • fdiv — Divides two numbers, according to IEEE 754
    • floor — Round fractions down
    • fmod — Returns the floating point remainder (modulo) of the division of the arguments
    • fpow — Raise one number to the power of another, according to IEEE 754
    • hexdec — Hexadecimal to decimal
    • hypot — Calculate the length of the hypotenuse of a right-angle triangle
    • intdiv — Integer division
    • is_finite — Checks whether a float is finite
    • is_infinite — Checks whether a float is infinite
    • is_nan — Checks whether a float is NAN
    • log — Natural logarithm
    • log10 — Base-10 logarithm
    • log1p — Returns log(1 + number), computed in a way that is accurate even when the value of number is close to zero
    • max — Find highest value
    • min — Find lowest value
    • octdec — Octal to decimal
    • pi — Get value of pi
    • pow — Exponential expression
    • rad2deg — Converts the radian number to the equivalent number in degrees
    • round — Rounds a float
    • sin — Sine
    • sinh — Hyperbolic sine
    • sqrt — Square root
    • tan — Tangent
    • tanh — Hyperbolic tangent

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    User Contributed Notes 2 notes

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    pat.mat AT sympatico DOT com
    21 years ago
    For people interest in Differential Equations, I've done a function that receive a string like: x^2+x^3 and put it in2x+3x^2 witch is the differantial of the previous equation.In the code there is one thing missing: the $string{$i} is often going outOfBound (Uninitialized string offset: 6 in...)if your error setting is set a little too high... I just dont know how to fix this.So there is the code for differential equation with (+ and -) only:<?function differentiel($equa){    $equa = strtolower($equa);    echo "Equation de depart: ".$equa."<br>";    $final = "";         for($i = 0; $i < strlen($equa); $i++)    {        //Make a new string from the receive $equa        if($equa{$i} == "x" && $equa{$i+1} == "^")        {            $final .= $equa{$i+2};            $final .= "x^";            $final .= $equa{$i+2}-1;        }        elseif($equa{$i} == "+" || $equa{$i} == "-")        {            $final .= $equa{$i};        }        elseif(is_numeric($equa{$i}) && $i == 0)        {            //gerer parenthese et autre terme generaux + gerer ^apres: 2^2            $final .= $equa{$i}."*";        }        elseif(is_numeric($equa{$i}) && $i > 0 && $equa{$i-1} != "^")        {            //gerer ^apres: 2^2            $final .= $equa{$i}."*";        }        elseif($equa{$i} == "^")        {            continue;        }        elseif(is_numeric($equa{$i}) && $equa{$i-1} == "^")        {            continue;        }        else        {            if($equa{$i} == "x")            {                $final .= 1;            }            else            {                $final .= $equa{$i};             }        }    }    //    //Manage multiplication add in the previous string $final    //    $finalMul = "";    for($i = 0; $i < strlen($final); $i++)    {        if(is_numeric($final{$i}) && $final{$i+1} == "*" && is_numeric($final{$i+2}))        {            $finalMul .= $final{$i}*$final{$i+2};        }        elseif($final{$i} == "*")        {            continue;        }        elseif(is_numeric($final{$i}) && $final{$i+1} != "*" && $final{$i-1} == "*")        {            continue;        }        else        {            $finalMul .= $final{$i};            }    }    echo "equa final: ".$finalMul;}?>I know this is not optimal but i've done this quick :)If you guys have any comment just email me.I also want to do this fonction In C to add to phpCore maybe soon...Patoff
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    7
    daniel at g-loc dot org
    19 years ago
    If you're an aviator and needs to calculate windcorrection angles and groundspeed (e.g. during flightplanning) this can be very useful.

$windcorrection = rad2deg(asin((($windspeed * (sin(deg2rad($tt - ($winddirection-180))))/$tas))));
$groundspeed = $tas*cos(deg2rad($windcorrection)) + $windspeed*cos(deg2rad($tt-($winddirection-180)));

You can probably write these lines more beautiful, but they work!
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