← All parts of this equation

Equation 28 · Part 6 · Einstein's Random Walk and the Mathematics of Genetic Drift

fraction

u(p)=1−e−4Nsp1−e−4Nsu(p) = \frac{1-e^{-4Nsp}}{1-e^{-4Ns}}
fraction

What this part means

Divide the expression above the line by the one below it.

Its job in the formula

The expression above the fraction bar is divided by the complete expression below it. The denominator must not be zero.

The passage around this formula

That machinery pays off in the cleanest result in the theory of drift. Kimura’s 1962 formula for the probability that a gene with selective advantage s eventually fixes, starting from frequency p in a population of effective size N , is u(p)=1−e−4Nsp1−e−4Nsu(p) = \frac{1-e^{-4Nsp}}{1-e^{-4Ns}}. as verified directly from his derivation [ 7 ] . Let the selective advantage vanish — the allele is neutral, indistinguishable from its alternatives in its effect on survival or reproduction — and the exponentials cancel term by term, leaving

Read this part in the article →

Learn the underlying idea

A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.

Open the illustrated fractions: division written vertically guide →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.