log1p
返回 log(1 + number),甚至当 number 的值接近零也能计算出准确结果
返回不同数值的 log(1+number) 计算结果:
<span class="token php language-php"><span class="token delimiter important"><?php</span> <span class="token keyword">echo</span><span class="token punctuation">(</span><span class="token function">log1p</span><span class="token punctuation">(</span><span class="token number">2.7183</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">echo</span><span class="token punctuation">(</span><span class="token function">log1p</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">echo</span><span class="token punctuation">(</span><span class="token function">log1p</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">echo</span><span class="token punctuation">(</span><span class="token function">log1p</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token delimiter important">?></span></span>