e (Euler's number) explanation, and applications

#math #statistics

It is quite well explained here -- https://betterexplained.com/articles/demystifying-the-natural-logarithm-ln/

Although, I don't truly understand, I see it as an attempt to calculate the compound interest curve; and natural logarithms as reverse calculating it.

Feel that this website is about right -- https://betterexplained.com/archives/ (and there are computer science problems, too.)

Though, another approach is to start from problems (thought or real).

BTW, my favorite in computer thingy might be,

float Q_rsqrt( float number )
{
    long i;
    float x2, y;
    const float threehalfs = 1.5F;

    x2 = number * 0.5F;
    y  = number;
    i  = * ( long * ) &y;                       // evil floating point bit level hacking
    i  = 0x5f3759df - ( i >> 1 );               // what the fuck? 
    y  = * ( float * ) &i;
    y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
//  y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}