<div dir="ltr"><div>Dear Dave</div><div><br></div><div>We have already converted all our cryo-EM software to 64 bits FP more than a decade ago.</div><div>The reason is simple: if you have a dataset consisting of say 1.000 images of 512x512 pixels and you would like to calculate the average density of the pixels in that data set that requires 9 significant digits. In 32 bits floating point only 6-7 significant digits are available...</div><div>Another example: The 3D FFT of an 800x800x800(=512.000.000) voxel 3D reconstruction will again require more than
9 significant digits. The tricky thing is that the floating-point underflows are rounded off to "0" and the users don't necessarily notice that the results are flawed.</div><div>More recently we have also implemented the double-precision FP also as an official IMAGIC disk format, although all FP calculations were already in 64bit FP for more than a decade.</div><div>Cheers<br></div><div>Marin</div><div>
<p class="MsoNormal" style="margin:0cm;text-align:justify;line-height:normal;font-size:11pt;font-family:"Calibri",sans-serif"><span lang="EN-IN" style="font-family:"Times New Roman",serif"><br></span></p><p class="MsoNormal" style="margin:0cm;text-align:justify;line-height:normal;font-size:11pt;font-family:"Calibri",sans-serif"><span lang="EN-IN" style="font-family:"Times New Roman",serif">Van Heel,
M., Portugal, R., Rohou, A., Linnemayr, C., Bebeacua, C., Schmidt, R., Grant,
T. & Schatz, M. (2012). Four-dimensional cryo-electron microscopy at
quasi-atomic resolution: <b><i>IMAGIC 4D</i></b>. <i>International Tables for
Crystallography</i>. <i>Vol. F, Chapter</i><b> 19.9,</b> 624–628. <span></span></span></p>
</div><div><br></div><div> <br></div><div><br>
</div><div><br></div><div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Dec 5, 2023 at 12:04 PM David Lawson (JIC) <<a href="mailto:david.lawson@jic.ac.uk">david.lawson@jic.ac.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg-5498539165603631333">
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<p class="MsoNormal">Hi All,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">This a request from a colleague who has been tasked with sourcing hardware for cryo-EM data processing. He is trying to work out a compromise between NVlink for memory sharing and 32/64bit Floating Point operations. Is 64bit FP needed or
likely to be important in the next 5 years or so?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Any advice would be much appreciated.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Many thanks<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Dave<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span>-------------------------------<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Prof. David M. Lawson<u></u><u></u></span></p>
<p class="MsoNormal"><span>Department of Biochemistry and Metabolism,<u></u><u></u></span></p>
<p class="MsoNormal"><span>John Innes Centre,<u></u><u></u></span></p>
<p class="MsoNormal"><span>Norwich,<u></u><u></u></span></p>
<p class="MsoNormal"><span>NR4 7UH, UK.<u></u><u></u></span></p>
<p class="MsoNormal"><span>Tel: +44-(0)1603-450725<u></u><u></u></span></p>
<p class="MsoNormal"><span>Web:
<a href="https://urldefense.com/v3/__https://www.jic.ac.uk/people/david-lawson__;!!Mih3wA!HIEoGvRHTL6Rcxv13u3aXIldgdmnsEQE3XgVp-YZoFIoTtsnHQu9kjsYnNL2uBRmwCck8TMTPknkTM0LO2pgJb5cGF2SJw$" target="_blank"><span style="color:rgb(5,99,193)">https://www.jic.ac.uk/people/david-lawson</span></a>
<u></u><u></u></span></p>
<p class="MsoNormal"><span>Email:
<a href="mailto:david.lawson@jic.ac.uk" target="_blank"><span style="color:rgb(5,99,193)">david.lawson@jic.ac.uk</span></a><u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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