``` 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
```
```// Copyright 2018-2020 argmin developers
//
// copied, modified, or distributed except according to those terms.

//! # References:
//!
//! [0] Jorge Nocedal and Stephen J. Wright (2006). Numerical Optimization.
//! Springer. ISBN 0-387-30303-0.

use crate::prelude::*;
use serde::{Deserialize, Serialize};
use std::fmt::Debug;

/// The Cauchy point is the minimum of the quadratic approximation of the cost function within the
/// trust region along the direction given by the first derivative.
///
/// # References:
///
/// [0] Jorge Nocedal and Stephen J. Wright (2006). Numerical Optimization.
/// Springer. ISBN 0-387-30303-0.
#[derive(Clone, Serialize, Deserialize, Debug, Copy, PartialEq, PartialOrd, Default)]
pub struct CauchyPoint<F> {
}

impl<F: ArgminFloat> CauchyPoint<F> {
/// Constructor
pub fn new() -> Self {
}
}

impl<O, F> Solver<O> for CauchyPoint<F>
where
O: ArgminOp<Output = F, Float = F>,
O::Param: Debug
+ Clone
+ Serialize
+ ArgminMul<O::Float, O::Param>
+ ArgminWeightedDot<O::Param, F, O::Hessian>
+ ArgminNorm<O::Float>,
O::Hessian: Clone + Serialize,
F: ArgminFloat,
{
const NAME: &'static str = "Cauchy Point";

fn next_iter(
&mut self,
op: &mut OpWrapper<O>,
state: &IterState<O>,
) -> Result<ArgminIterData<O>, Error> {
let param = state.get_param();
let hessian = state
.get_hessian()
.unwrap_or_else(|| op.hessian(&param).unwrap());

let tau: F = if wdp <= F::from_f64(0.0).unwrap() {
F::from_f64(1.0).unwrap()
} else {
F::from_f64(1.0)
.unwrap()
};

Ok(ArgminIterData::new().param(new_param))
}

fn terminate(&mut self, state: &IterState<O>) -> TerminationReason {
if state.get_iter() >= 1 {
TerminationReason::MaxItersReached
} else {
TerminationReason::NotTerminated
}
}
}

impl<F: ArgminFloat> ArgminTrustRegion<F> for CauchyPoint<F> {