How to Properly Use PHP’s log10 Function? Complete Usage Guide and Example Explanation

gitbox 2025-07-28

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// This document’s sample code demonstrates how to use PHP’s log10 function</span></span><span>
</span><span><span class="hljs-meta">?&gt;</span></span><span>
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<p></span># How to Properly Use PHP’s log10 Function? Complete Usage Guide and Example Explanation<span></p>
<p>In PHP, the <code>log10

Parameter $number: Must be a floating-point number or integer greater than 0.
Return value: Returns the base 10 logarithm of $number.
Note: If the argument passed is less than or equal to 0, the function will return NAN (Not A Number).

2. Usage Examples

Example 1: Calculate log10 of 100

<span><span><span class="hljs-variable">$number</span></span><span> = </span><span><span class="hljs-number">100</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">log10</span></span><span>(</span><span><span class="hljs-variable">$number</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"log10(<span class="hljs-subst">$number</span>) = " . </span><span><span class="hljs-variable">$result</span></span><span>;  </span><span><span class="hljs-comment">// Output: log10(100) = 2</span></span><span>
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Explanation: Since $10^2 = 100$ 102=100, the result of log10(100) is 2.

Example 2: Calculate log10 of 0.01

<span><span><span class="hljs-variable">$number</span></span><span> = </span><span><span class="hljs-number">0.01</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">log10</span></span><span>(</span><span><span class="hljs-variable">$number</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"log10(<span class="hljs-subst">$number</span>) = " . </span><span><span class="hljs-variable">$result</span></span><span>;  </span><span><span class="hljs-comment">// Output: log10(0.01) = -2</span></span><span>
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Explanation: Since $10^{-2} = 0.01$ class="katex-html" aria-hidden="true">10-2=0.01, the result is -2.

Example 3: Handling Invalid Input

<span><span><span class="hljs-variable">$number</span></span><span> = -</span><span><span class="hljs-number">5</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">log10</span></span><span>(</span><span><span class="hljs-variable">$number</span></span><span>);

</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">is_nan</span></span><span>(</span><span><span class="hljs-variable">$result</span></span><span>)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Input value must be greater than 0; current value is <span class="hljs-subst">$number</span>, unable to calculate log10.";
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"log10(<span class="hljs-subst">$number</span>) = " . </span><span><span class="hljs-variable">$result</span></span><span>;
}
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In this example, the input is negative, so the function returns NAN. We use is_nan to check and display an appropriate message.

3. Summary

log10 calculates the base 10 logarithm and requires the parameter to be greater than 0.
Commonly used in mathematics, physics, and engineering for logarithmic transformations.
Be mindful of the input range to avoid invalid results.

Once you master the use of log10, you can easily handle various logarithmic calculations and improve the mathematical capabilities of your code.

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log10
is_nan