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<div class="moz-cite-prefix">Hi Nacho,<br>
<br>
If what you want is to produce a rounded <i>print string</i>,
rather than a rounded<i> number</i>, one can use a formatted
printing message, such as #printShowingDecimalPlaces:.<br>
<br>
Regards,<br>
-Martin<br>
<br>
On 3/6/23 04:03, Ignacio Sniechowski wrote:<br>
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<div class="gmail_default"
style="font-family:monospace;font-size:large">Thanks for your
response, Martin!</div>
<div class="gmail_default"
style="font-family:monospace;font-size:large">I thought that
#roundTo: only affected representation, but it seems that
there are some caveats when applied to floatings.</div>
<div class="gmail_default"
style="font-family:monospace;font-size:large">I've
experimented with 0.1, 0.01, and 0.001, and this
misrepresentation affects other numbers in the interval. So
the lesson would be: be careful with #roundUp: & similar
methods when using floating as the imagined or expected
representation could fail.</div>
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style="font-family:monospace;font-size:large"><br>
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<div class="gmail_default"
style="font-family:monospace;font-size:large">Thanks again</div>
<div class="gmail_default"
style="font-family:monospace;font-size:large">Nacho</div>
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<div><b><font size="2">Ignacio
Sniechowski</font></b><b><br>
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<div dir="ltr" class="gmail_attr">On Sun, Mar 5, 2023 at
10:34 PM Martin McClure <<a
href="mailto:martin@hand2mouse.com" moz-do-not-send="true"
class="moz-txt-link-freetext">martin@hand2mouse.com</a>>
wrote:<br>
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<div>On 3/5/23 16:51, Ignacio Sniechowski via Cuis-dev
wrote:<br>
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<blockquote type="cite">
<div class="gmail_default"
style="font-family:monospace;font-size:large"><span
style="color:rgb(0,0,0);font-size:9pt;font-family:CMTT9">Float
pi to: 5 by: 1/3 do: [:i | Transcript show: (i
roundTo: 0.01) ; space]<span> </span></span><span
style="color:rgb(0,0,0);font-size:9pt;font-family:CMSY9">⇒<span> </span></span><span
style="color:rgb(0,0,0);font-size:9pt;font-family:CMTT9">3.14 3.47 3.81
4.14 4.47 4.81</span> </div>
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<div><b><font size="2"><span
class="gmail_default" style="font-family:monospace;font-size:large">"</span></font></b><b><font
size="2"><span
class="gmail_default"
style="font-family:monospace;font-size:large"></span></font></b>3.14
3.47 3.81 4.14 4.47
4.8100000000000005<span
class="gmail_default"
style="font-family:monospace;font-size:large">"
the last number is not
rounded...</span></div>
<div><span
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style="font-family:monospace;font-size:large">What
is especially intriguing
is the last case...that
4.8100000000000005 is
not rounded.</span></div>
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<br>
Hi Nacho,<br>
<br>
Ah, welcome the lovely and confusing world of decimal
expressions of binary floating-point numbers. <br>
<br>
What is not obvious here is that the last case <i>is</i>
rounded. <br>
<br>
"roundTo: 0.01" requests that the result be an exact
multiple of 0.01. But 0.01 is not exactly representable as a
floating-point number, so the closest Float is used, and
that float is a bit greater than 1/100. <br>
<br>
0.01 asFraction > (1/100) ==> true<br>
<br>
So we end up with a float that is 481 * 0.01, which is a
little more than 481 / 100, <i>and</i> there exists a
different float which is closer to 481 / 100. Every float
has a unique default print string. The string '4.81' is used
for that other float, so we have to use the string
'4.8100000000000005' for the float that is the correct
result of the expression.<br>
<br>
Regards,<br>
-Martin<br>
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