[−][src]Function roots::find_root_inverse_quadratic
pub fn find_root_inverse_quadratic<F, Func>(
a: F,
b: F,
f: Func,
convergency: &mut dyn Convergency<F>
) -> Result<F, SearchError> where
F: FloatType,
Func: Fn(F) -> F,
Find a root of the function f(x) = 0 using inverse quadratic approximation.
Pro
- Faster than linear approximation
- No need for derivative function
Contra
- sqrt is calculated on every step
- only works for polynomial-like functions
Failures
NoBracketing
Initial values do not bracket the root.
NoConvergency
Algorithm cannot find a root within the given number of iterations.
Examples
use roots::SimpleConvergency; use roots::find_root_inverse_quadratic; let f = |x| { 1f64*x*x - 1f64 }; let mut convergency = SimpleConvergency { eps:1e-15f64, max_iter:30 }; let root1 = find_root_inverse_quadratic(10f64, 0f64, &f, &mut convergency); // Returns approximately Ok(1); let root2 = find_root_inverse_quadratic(-10f64, 0f64, &f, &mut 1e-15f64); // Returns approximately Ok(-1);