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</pre><pre class="rust"><code><span class="kw">use </span><span class="kw">super</span>::expf;
<span class="comment">/* k is such that k*ln2 has minimal relative error and x - kln2 &gt; log(FLT_MIN) */
</span><span class="kw">const </span>K: i32 = <span class="number">235</span>;
<span class="comment">/* expf(x)/2 for x &gt;= log(FLT_MAX), slightly better than 0.5f*expf(x/2)*expf(x/2) */
</span><span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>k_expo2f(x: f32) -&gt; f32 {
<span class="kw">let </span>k_ln2 = f32::from_bits(<span class="number">0x4322e3bc</span>);
<span class="comment">/* note that k is odd and scale*scale overflows */
</span><span class="kw">let </span>scale = f32::from_bits(((<span class="number">0x7f </span>+ K / <span class="number">2</span>) <span class="kw">as </span>u32) &lt;&lt; <span class="number">23</span>);
<span class="comment">/* exp(x - k ln2) * 2**(k-1) */
</span>expf(x - k_ln2) * scale * scale
}
</code></pre></div>
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