来自数学公式的 C++ 数学表达式

Question

I try to convert this math formula in C++ expression

But I'm doing something wrong

(log(1.0+a*(getpixel(j,k)))/log10( y ))/(log(2.0)/log10( y ))

Answer 1

First, the log function already computes the logarithm to the base e . You don't need to perform any change-of-base.

Second, split your expression into parts to make it easier to write, and to understand:

const double F = getpixel(j, k);
const double numerator = log(1.0 + a * F);
const double denominator = log(2.0);
const double result = numerator / denominator;

You could choose to split it more (eg store the a*F , and 1 + a*F separately too).

Once you've got that, if you really want it in a single line, it's easy enough to combine (but there's no need; the compiler will typically merge constant expressions together for you):

const double result = log(1.0 + a * getpixel(j, k) / log(2.0);