Fri, 18 Nov 2022 10:29:50 +0200
Improvements and minor fixes to bisection tree refinement.
/*! Arithmetic functions that are valid in a ‘const context”, i.e., can be computed at compile-time. */ /// Calculate $n!$. Valid in a const-context. /// /// (The version in the crate `num_integer` deesn't currently work in a const-context.) pub const fn factorial(n : usize) -> usize { const fn f(i : usize, a : usize) -> usize { if i==0 { a } else { f(i-1, i*a) } } f(n, 1) } /// Calculate $n \choose k$. Valid in a const-context. /// /// (The version in the crate `num_integer` doesn't currently work in a const-context.) pub const fn binomial(n : usize, k : usize) -> usize { factorial(n)/(factorial(n-k)*factorial(k)) } /// Calculate $n^k$. Valid in a const-context. /// /// (The version in the crate `num_integer` doesn't currently work in a const-context.) pub const fn pow(n : usize, k : usize) -> usize { const fn pow_accum(n : usize, k : usize, accum : usize) -> usize { if k==0 { accum } else { pow_accum(n, k-1, accum*n) } } pow_accum(n, k, 1) }