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</pre><pre class="rust"><code><span class="doccomment">//! Module for the fmincg optimization algorithm.
//!
//! This algorithm was taken from Andrew Ng&#39;s coursera machine
//! learning course. The function was translated from MATLAB into rust.
//! Original source code can be found [here](http://www.mathworks.com/matlabcentral/fileexchange/42770-logistic-regression-with-regularization-used-to-classify-hand-written-digits/content/Logistic%20Regression%20with%20regularisation/fmincg.m).
//!
//! The attached license permits use and modification for research
//! and education only.
//!
//! Copyright (C) 2001 and 2002 by Carl Edward Rasmussen. Date 2002-02-13
//!
//!
//! (C) Copyright 1999, 2000 &amp; 2001, Carl Edward Rasmussen
//!
//! Permission is granted for anyone to copy, use, or modify these
//! programs and accompanying documents for purposes of research or
//! education, provided this copyright notice is retained, and note is
//! made of any changes that have been made.
//!
//! These programs and documents are distributed without any warranty,
//! express or implied. As the programs were written for research
//! purposes only, they have not been tested to the degree that would be
//! advisable in any important application. All use of these programs is
//! entirely at the user&#39;s own risk.
//!
//! [rusty-machine] Changes made:
//!
//! - Conversion to Rust.
//! - Length hard defaults to the max iterations.
</span><span class="kw">use </span>learning::optim::{Optimizable, OptimAlgorithm};
<span class="kw">use </span>linalg::Vector;
<span class="kw">use </span>std::cmp;
<span class="kw">use </span>std::f64;
<span class="doccomment">/// Conjugate Gradient Descent algorithm
</span><span class="attribute">#[derive(Clone, Copy, Debug)]
</span><span class="kw">pub struct </span>ConjugateGD {
<span class="doccomment">/// Constant in the Wolfe-Powell conditions.
</span><span class="kw">pub </span>rho: f64,
<span class="doccomment">/// Constant in the Wolfe-Powell conditions.
</span><span class="kw">pub </span>sig: f64,
<span class="doccomment">/// Don&#39;t reevaluate within `int` of the limit of the current bracket.
</span><span class="kw">pub </span>int: f64,
<span class="doccomment">/// Extrapolate max of `ext` times the current bracket.
</span><span class="kw">pub </span>ext: f64,
<span class="doccomment">/// Max of `max` function evaluations per line search
</span><span class="kw">pub </span>max: usize,
<span class="doccomment">/// The maximum allowed slope ratio
</span><span class="kw">pub </span>ratio: f64,
<span class="doccomment">/// The default number of max iterations.
</span><span class="kw">pub </span>iters: usize,
}
<span class="doccomment">/// The default Conjugate GD algorithm.
///
/// The defaults are:
///
/// - rho = 0.01
/// - sig = 0.5
/// - int = 0.1
/// - ext = 3
/// - max = 20
/// - ration = 100
/// - iters = 100
</span><span class="kw">impl </span>Default <span class="kw">for </span>ConjugateGD {
<span class="kw">fn </span>default() -&gt; ConjugateGD {
ConjugateGD {
rho: <span class="number">0.01</span>,
sig: <span class="number">0.5</span>,
int: <span class="number">0.1</span>,
ext: <span class="number">3.0</span>,
max: <span class="number">20</span>,
ratio: <span class="number">100.0</span>,
iters: <span class="number">100</span>,
}
}
}
<span class="kw">impl</span>&lt;M: Optimizable&gt; OptimAlgorithm&lt;M&gt; <span class="kw">for </span>ConjugateGD {
<span class="kw">fn </span>optimize(<span class="kw-2">&amp;</span><span class="self">self</span>,
model: <span class="kw-2">&amp;</span>M,
start: <span class="kw-2">&amp;</span>[f64],
inputs: <span class="kw-2">&amp;</span>M::Inputs,
targets: <span class="kw-2">&amp;</span>M::Targets)
-&gt; Vec&lt;f64&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>i = <span class="number">0usize</span>;
<span class="kw">let </span><span class="kw-2">mut </span>ls_failed = <span class="bool-val">false</span>;
<span class="kw">let </span>(<span class="kw-2">mut </span>f1, vec_df1) = model.compute_grad(start, inputs, targets);
<span class="kw">let </span><span class="kw-2">mut </span>df1 = Vector::new(vec_df1);
<span class="comment">// The reduction in the function. Can also be specified as part of length
</span><span class="kw">let </span>red = <span class="number">1f64</span>;
<span class="kw">let </span>length = <span class="self">self</span>.iters <span class="kw">as </span>i32;
<span class="kw">let </span><span class="kw-2">mut </span>s = -df1.clone();
<span class="kw">let </span><span class="kw-2">mut </span>d1 = -s.dot(<span class="kw-2">&amp;</span>s);
<span class="kw">let </span><span class="kw-2">mut </span>z1 = red / (<span class="number">1f64 </span>- d1);
<span class="kw">let </span><span class="kw-2">mut </span>x = Vector::new(start.to_vec());
<span class="kw">let </span>(<span class="kw-2">mut </span>f2, <span class="kw-2">mut </span>df2): (f64, Vector&lt;f64&gt;);
<span class="kw">while </span>(i <span class="kw">as </span>i32) &lt; length.abs() {
<span class="kw">if </span>length &gt; <span class="number">0 </span>{
i += <span class="number">1</span>;
}
<span class="kw">let </span>(x0, f0) = (x.clone(), f1);
x += <span class="kw-2">&amp;</span>s * z1;
<span class="kw">let </span>cost = model.compute_grad(x.data(), inputs, targets);
f2 = cost.<span class="number">0</span>;
df2 = Vector::new(cost.<span class="number">1</span>);
<span class="kw">if </span>length &lt; <span class="number">0 </span>{
i += <span class="number">1</span>;
}
<span class="kw">let </span><span class="kw-2">mut </span>d2 = df2.dot(<span class="kw-2">&amp;</span>s);
<span class="kw">let </span>(<span class="kw-2">mut </span>f3, <span class="kw-2">mut </span>d3, <span class="kw-2">mut </span>z3) = (f1, d1, -z1);
<span class="kw">let </span><span class="kw-2">mut </span>m = <span class="kw">if </span>length &gt; <span class="number">0 </span>{
<span class="self">self</span>.max <span class="kw">as </span>i32
} <span class="kw">else </span>{
cmp::min(<span class="self">self</span>.max <span class="kw">as </span>i32, -length - (i <span class="kw">as </span>i32))
};
<span class="kw">let </span><span class="kw-2">mut </span>success = <span class="bool-val">false</span>;
<span class="kw">let </span><span class="kw-2">mut </span>limit = -<span class="number">1f64</span>;
<span class="kw">loop </span>{
<span class="kw">let </span><span class="kw-2">mut </span>z2: f64;
<span class="kw">while </span>((f2 &gt; (f1 + z1 * <span class="self">self</span>.rho * d1)) || (d2 &gt; -<span class="self">self</span>.sig * d1)) &amp;&amp; (m &gt; <span class="number">0i32</span>) {
limit = z1;
<span class="kw">if </span>f2 &gt; f1 {
z2 = z3 - (<span class="number">0.5 </span>* d3 * z3 * z3) / (d3 * z3 + f2 - f3);
} <span class="kw">else </span>{
<span class="kw">let </span>a = <span class="number">6f64 </span>* (f2 - f3) / z3 + <span class="number">3f64 </span>* (d2 + d3);
<span class="kw">let </span>b = <span class="number">3f64 </span>* (f3 - f2) - z3 * (<span class="number">2f64 </span>* d2 + d3);
z2 = ((b * b - a * d2 * z3 * z3).sqrt() - b) / a;
}
<span class="kw">if </span>z2.is_nan() || z2.is_infinite() {
z2 = z3 / <span class="number">2f64</span>;
}
<span class="kw">if </span>z2 &lt;= <span class="self">self</span>.int * z3 {
<span class="kw">if </span>z2 &lt;= (<span class="number">1f64 </span>- <span class="self">self</span>.int) * z3 {
z2 = (<span class="number">1f64 </span>- <span class="self">self</span>.int) * z3;
}
} <span class="kw">else if </span><span class="self">self</span>.int * z3 &lt;= (<span class="number">1f64 </span>- <span class="self">self</span>.int) * z3 {
z2 = (<span class="number">1f64 </span>- <span class="self">self</span>.int) * z3;
} <span class="kw">else </span>{
z2 = <span class="self">self</span>.int * z3;
}
z1 += z2;
x += <span class="kw-2">&amp;</span>s * z2;
<span class="kw">let </span>cost_grad = model.compute_grad(x.data(), inputs, targets);
f2 = cost_grad.<span class="number">0</span>;
df2 = Vector::new(cost_grad.<span class="number">1</span>);
m -= <span class="number">1i32</span>;
<span class="kw">if </span>length &lt; <span class="number">0 </span>{
i += <span class="number">1</span>;
}
d2 = df2.dot(<span class="kw-2">&amp;</span>s);
z3 -= z2;
}
<span class="kw">if </span>f2 &gt; f1 + z1 * <span class="self">self</span>.rho * d1 || d2 &gt; -<span class="self">self</span>.sig * d1 {
<span class="kw">break</span>;
} <span class="kw">else if </span>d2 &gt; <span class="self">self</span>.sig * d1 {
success = <span class="bool-val">true</span>;
<span class="kw">break</span>;
} <span class="kw">else if </span>m == <span class="number">0i32 </span>{
<span class="kw">break</span>;
}
<span class="kw">let </span>a = <span class="number">6f64 </span>* (f2 - f3) / z3 + <span class="number">3f64 </span>* (d2 + d3);
<span class="kw">let </span>b = <span class="number">3f64 </span>* (f3 - f2) - z3 * (<span class="number">2f64 </span>* d2 + d3);
z2 = -d2 * z3 * z3 / (b + (b * b - a * d2 * z3 * z3).sqrt());
<span class="kw">if </span>z2.is_nan() || z2.is_infinite() || z2 &lt; <span class="number">0f64 </span>{
<span class="kw">if </span>limit &lt; -<span class="number">0.5 </span>{
z2 = z1 * (<span class="self">self</span>.ext - <span class="number">1f64</span>);
} <span class="kw">else </span>{
z2 = (limit - z1) / <span class="number">2f64</span>;
}
} <span class="kw">else if </span>(limit &gt; -<span class="number">0.5</span>) &amp;&amp; (z2 + z1 &gt; limit) {
z2 = (limit - z1) / <span class="number">2f64</span>;
} <span class="kw">else if </span>(limit &lt; -<span class="number">0.5</span>) &amp;&amp; (z2 + z1 &gt; z1 * <span class="self">self</span>.ext) {
z2 = z1 * (<span class="self">self</span>.ext - <span class="number">1f64</span>);
} <span class="kw">else if </span>z2 &lt; -z3 * <span class="self">self</span>.int {
z2 = -z3 * <span class="self">self</span>.int;
} <span class="kw">else if </span>(limit &gt; -<span class="number">0.5</span>) &amp;&amp; (z2 &lt; (limit - z1) * (<span class="number">1f64 </span>- <span class="self">self</span>.int)) {
z2 = (limit - z1) * (<span class="number">1f64 </span>- <span class="self">self</span>.int);
}
f3 = f2;
d3 = d2;
z3 = -z2;
z1 += z2;
x += <span class="kw-2">&amp;</span>s * z2;
<span class="kw">let </span>cost_grad = model.compute_grad(x.data(), inputs, targets);
f2 = cost_grad.<span class="number">0</span>;
df2 = Vector::new(cost_grad.<span class="number">1</span>);
m -= <span class="number">1</span>;
<span class="kw">if </span>length &lt; <span class="number">0 </span>{
i += <span class="number">1</span>;
}
d2 = df2.dot(<span class="kw-2">&amp;</span>s);
}
<span class="kw">if </span>success {
f1 = f2;
s = s * (<span class="kw-2">&amp;</span>df2 - <span class="kw-2">&amp;</span>df1).dot(<span class="kw-2">&amp;</span>df2) / df1.dot(<span class="kw-2">&amp;</span>df1) - <span class="kw-2">&amp;</span>df2;
df1 = df2;
d2 = df1.dot(<span class="kw-2">&amp;</span>s);
<span class="kw">if </span>d2 &gt; <span class="number">0f64 </span>{
s = -<span class="kw-2">&amp;</span>df1;
d2 = -s.dot(<span class="kw-2">&amp;</span>s);
}
<span class="kw">let </span>ratio = d1 / (d2 - f64::MIN_POSITIVE);
<span class="kw">if </span><span class="self">self</span>.ratio &lt; ratio {
z1 <span class="kw-2">*</span>= <span class="self">self</span>.ratio;
} <span class="kw">else </span>{
z1 <span class="kw-2">*</span>= ratio;
}
d1 = d2;
ls_failed = <span class="bool-val">false</span>;
} <span class="kw">else </span>{
x = x0;
f1 = f0;
<span class="kw">if </span>ls_failed || i <span class="kw">as </span>i32 &gt; length.abs() {
<span class="kw">break</span>;
}
df1 = df2;
s = -<span class="kw-2">&amp;</span>df1;
d1 = -s.dot(<span class="kw-2">&amp;</span>s);
z1 = <span class="number">1f64 </span>/ (<span class="number">1f64 </span>- d1);
ls_failed = <span class="bool-val">true</span>;
}
}
x.into_vec()
}
}
</code></pre></div>
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