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<div style="direction: ltr;">Hi Ram,</div>
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<div style="direction: ltr;">No, NumPy doesnít have a way. And it newer versions, it probably wonít create two arrays if all the dtypes match, itíll do some magic to re use the existing ones, although it will use multiple loops instead of just one.</div>
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<div style="direction: ltr;">You might want to look into NumExpr or Numba if you want an efficient implementation.</div>
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<div id="divRplyFwdMsg" dir="dir="ltr""><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> NumPy-Discussion <numpy-discussion-bounces+einstein.edison=gmail.com@python.org> on behalf of Ram Rachum <ram@rachum.com><br>
<b>Sent:</b> Tuesday, July 23, 2019 7:29 pm<br>
<b>To:</b> numpy-discussion@python.org<br>
<b>Subject:</b> [Numpy-discussion] Creating a sine wave with exponential decay
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Hi everyone! Total <span class="gmail-il">Numpy</span> newbie here.</p>
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I'd like to create an array with a million numbers, that has a sine wave with exponential decay on the amplitude.</p>
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In other words, I want the value of each cell <code style="margin:0px; padding:1px 5px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif; font-size:13px; vertical-align:baseline; box-sizing:inherit; background-color:rgb(239,240,241); white-space:pre-wrap">n</code> to
 be <code style="margin:0px; padding:1px 5px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif; font-size:13px; vertical-align:baseline; box-sizing:inherit; background-color:rgb(239,240,241); white-space:pre-wrap">sin(n)
 * 2 ** (-n * factor)</code>.</p>
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What would be the most efficient way to do that?</p>
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Someone suggested I do something like this: </p>
<pre class="gmail-m_3550683175654527263gmail-lang-py gmail-m_3550683175654527263gmail-prettyprint gmail-m_3550683175654527263gmail-prettyprinted" style="white-space:pre-wrap; margin-top:0px; margin-bottom:1em; padding:12px 8px; border:0px; font-variant-numeric:inherit; font-variant-east-asian:inherit; font-stretch:inherit; line-height:inherit; font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif; font-size:13px; vertical-align:baseline; box-sizing:inherit; width:auto; max-height:600px; overflow:auto; background-color:rgb(239,240,241); border-radius:3px; color:rgb(57,51,24)"><code style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif; vertical-align:baseline; box-sizing:inherit; white-space:inherit"><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">y </span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">=</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)"> np</span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">.</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">sin</span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">(</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">x</span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">)</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)"> </span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">*</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)"> np</span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">.</span><span class="gmail-m_3550683175654527263gmail-pln" style="margin:0px; padding:0px; border:0px; font-style:inherit; font-variant:inherit; font-weight:inherit; font-stretch:inherit; line-height:inherit; font-family:inherit; vertical-align:baseline; box-sizing:inherit; color:rgb(48,51,54)">exp</span><span class="gmail-m_3550683175654527263gmail-pun" style="margin:0px; padding:0px; border:0p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But this would create 2 arrays, wouldn't it? Isn't that wasteful? Does <span class="gmail-il">Numpy</span> provide an efficient way of doing that without creating a redundant array?</p>
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Thanks for your help,</p>
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Ram Rachum.</p>
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