284 lines
17 KiB
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284 lines
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<title>CMSIS-DSP: Square Root</title>
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<div id="projectname">CMSIS-DSP
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 <span id="projectnumber">Version 1.5.2</span>
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<div id="projectbrief">CMSIS DSP Software Library</div>
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<a href="#func-members">Functions</a> </div>
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<div class="title">Square Root<div class="ingroups"><a class="el" href="group__groupFastMath.html">Fast Math Functions</a></div></div> </div>
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</div><!--header-->
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<div class="contents">
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<table class="memberdecls">
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
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Functions</h2></td></tr>
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<tr class="memitem:ga697d82c2747a3302cf44e7c9583da2e8"><td class="memItemLeft" align="right" valign="top">CMSIS_INLINE __STATIC_INLINE <br class="typebreak"/>
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<a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__SQRT.html#ga697d82c2747a3302cf44e7c9583da2e8">arm_sqrt_f32</a> (<a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> in, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> *pOut)</td></tr>
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<tr class="memdesc:ga697d82c2747a3302cf44e7c9583da2e8"><td class="mdescLeft"> </td><td class="mdescRight">Floating-point square root function. <a href="#ga697d82c2747a3302cf44e7c9583da2e8">More...</a><br/></td></tr>
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<tr class="separator:ga697d82c2747a3302cf44e7c9583da2e8"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga119e25831e141d734d7ef10636670058"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__SQRT.html#ga119e25831e141d734d7ef10636670058">arm_sqrt_q31</a> (<a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> in, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> *pOut)</td></tr>
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<tr class="memdesc:ga119e25831e141d734d7ef10636670058"><td class="mdescLeft"> </td><td class="mdescRight">Q31 square root function. <a href="#ga119e25831e141d734d7ef10636670058">More...</a><br/></td></tr>
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<tr class="separator:ga119e25831e141d734d7ef10636670058"><td class="memSeparator" colspan="2"> </td></tr>
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<tr class="memitem:ga5abe5ca724f3e15849662b03752c1238"><td class="memItemLeft" align="right" valign="top"><a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="group__SQRT.html#ga5abe5ca724f3e15849662b03752c1238">arm_sqrt_q15</a> (<a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> in, <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> *pOut)</td></tr>
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<tr class="memdesc:ga5abe5ca724f3e15849662b03752c1238"><td class="mdescLeft"> </td><td class="mdescRight">Q15 square root function. <a href="#ga5abe5ca724f3e15849662b03752c1238">More...</a><br/></td></tr>
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<tr class="separator:ga5abe5ca724f3e15849662b03752c1238"><td class="memSeparator" colspan="2"> </td></tr>
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</table>
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<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
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<p>Computes the square root of a number. There are separate functions for Q15, Q31, and floating-point data types. The square root function is computed using the Newton-Raphson algorithm. This is an iterative algorithm of the form: </p>
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<pre>
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x1 = x0 - f(x0)/f'(x0)
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</pre><p> where <code>x1</code> is the current estimate, <code>x0</code> is the previous estimate, and <code>f'(x0)</code> is the derivative of <code>f()</code> evaluated at <code>x0</code>. For the square root function, the algorithm reduces to: </p>
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<pre>
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x0 = in/2 [initial guess]
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x1 = 1/2 * ( x0 + in / x0) [each iteration]
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</pre> <h2 class="groupheader">Function Documentation</h2>
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<a class="anchor" id="ga697d82c2747a3302cf44e7c9583da2e8"></a>
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<td class="memname">CMSIS_INLINE __STATIC_INLINE <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_sqrt_f32 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> </td>
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<td class="paramname"><em>in</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> * </td>
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<td class="paramname"><em>pOut</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">in</td><td>input value. </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">pOut</td><td>square root of input value. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if <code>in</code> is negative value and returns zero output for negative values. </dd></dl>
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<p>References <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a>, and <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a>.</p>
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<p>Referenced by <a class="el" href="group__cmplx__mag.html#gae45024c497392cde2ae358a76d435213">arm_cmplx_mag_f32()</a>, <a class="el" href="group__RMS.html#ga0e3ab1b57da32d45388d1fa90d7fd88c">arm_rms_f32()</a>, and <a class="el" href="group__STD.html#ga4969b5b5f3d001377bc401a3ee99dfc2">arm_std_f32()</a>.</p>
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</div>
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</div>
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<a class="anchor" id="ga5abe5ca724f3e15849662b03752c1238"></a>
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<div class="memitem">
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<td class="memname"><a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_sqrt_q15 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> </td>
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<td class="paramname"><em>in</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> * </td>
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<td class="paramname"><em>pOut</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">in</td><td>input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF. </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">pOut</td><td>square root of input value. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if <code>in</code> is negative value and returns zero output for negative values.</dd></dl>
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">in</td><td>input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF. </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">*pOut</td><td>square root of input value. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>The function returns ARM_MATH_SUCCESS if the input value is positive and ARM_MATH_ARGUMENT_ERROR if the input is negative. For negative inputs, the function returns *pOut = 0. </dd></dl>
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<p>References <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a>, and <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a>.</p>
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<p>Referenced by <a class="el" href="group__cmplx__mag.html#ga0a4a8f77a6a51d9b3f3b9d729f85b7a4">arm_cmplx_mag_q15()</a>, <a class="el" href="group__RMS.html#gaf5b836b72dda9e5dfbbd17c7906fd13f">arm_rms_q15()</a>, and <a class="el" href="group__STD.html#gaf9d27afa9928ff28a63cd98ea9218a72">arm_std_q15()</a>.</p>
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</div>
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</div>
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<a class="anchor" id="ga119e25831e141d734d7ef10636670058"></a>
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<td class="memname"><a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6">arm_status</a> arm_sqrt_q31 </td>
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<td>(</td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> </td>
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<td class="paramname"><em>in</em>, </td>
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</tr>
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<tr>
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<td class="paramkey"></td>
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<td></td>
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<td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> * </td>
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<td class="paramname"><em>pOut</em> </td>
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</tr>
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<tr>
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<td></td>
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<td>)</td>
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<td></td><td></td>
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</tr>
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</table>
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</div><div class="memdoc">
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">in</td><td>input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF. </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">pOut</td><td>square root of input value. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if <code>in</code> is negative value and returns zero output for negative values.</dd></dl>
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<dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramdir">[in]</td><td class="paramname">in</td><td>input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF. </td></tr>
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<tr><td class="paramdir">[out]</td><td class="paramname">*pOut</td><td>square root of input value. </td></tr>
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</table>
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</dd>
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</dl>
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<dl class="section return"><dt>Returns</dt><dd>The function returns ARM_MATH_SUCCESS if the input value is positive and ARM_MATH_ARGUMENT_ERROR if the input is negative. For negative inputs, the function returns *pOut = 0. </dd></dl>
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<p>References <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a74897e18d4b8f62b12a7d8a01dd2bb35">ARM_MATH_ARGUMENT_ERROR</a>, and <a class="el" href="arm__math_8h.html#a5e459c6409dfcd2927bb8a57491d7cf6a9f8b2a10bd827fb4600e77d455902eb0">ARM_MATH_SUCCESS</a>.</p>
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<p>Referenced by <a class="el" href="group__cmplx__mag.html#ga14f82f9230e9d96d5b9774e2fefcb7be">arm_cmplx_mag_q31()</a>, <a class="el" href="group__RMS.html#gae33015fda23fc44e7ead5e5ed7e8d314">arm_rms_q31()</a>, and <a class="el" href="group__STD.html#ga39495e74f96116178be085c9dc7742f5">arm_std_q31()</a>.</p>
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<img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.8.6
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