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    <p>I don't think the answer given by willm1 is correct.<br> Let me explain. </p> <p>The following expression:<br> <code>tlf.z &gt;= tlb.z - EPSILON</code><br> is equivalent to:<br> <code>(tlf.z &gt; tlb.z - EPSILON) or (tlf.z == tlb.z - EPSILON)</code></p> <p>If <code>tlf.z &gt; tlb.z</code> is true, even by a difference smaller than EPSILON, then <code>tlf.z &gt; tlb.z - EPSILON</code> will also be true. No matter what the value of EPSILON. Instead, the correct form is:<br> <code>tlf.z &gt; tlb.z + EPSILON</code><br> As for the second expression, <code>tlf.z == tlb.z - EPSILON</code>, it will only be evaluated as true if <code>tlf.z</code> and <code>tlb.z</code> differ exactly by <code>EPSILON</code>, which is not what we want. Instead, we want the difference between them to be less than <code>EPSILON</code>:<br> <code>abs(tlf.z - tlb.z) &lt;= EPSILON</code> </p> <p>Concluding, <code>tlf.z &gt;= tlb.z - EPSILON</code> should be written as:<br> <code>(tlf.z &gt; tlb.z + EPSILON) || (abs(tlf.z - tlb.z) &lt;= EPSILON)</code></p> <p><strong>Update</strong>:<br> I was looking at some code, and all of a sudden I noticed that <code>(tlf.z &gt; tlb.z + EPSILON) || (abs(tlf.z - tlb.z) &lt;= EPSILON)</code> is actually equivalent to <code>tlf.z &gt;= tlb.z - EPSILON</code>.<br> When we're looking for the similarity, <code>abs(tlf.z - tlb.z) &lt;= EPSILON</code>, we want <code>tlb.z</code> to be in the following gray area:<br> <img src="https://dl.dropbox.com/u/8799475/images/sim_2.png" width="400" height="100"><br> When we're looking for <code>tlf.z &gt; tlb.z + EPSILON</code>:<br> <img src="https://dl.dropbox.com/u/8799475/images/greater.png" width="400" height="100"><br> Hence, we're really looking for:<br> <img src="https://dl.dropbox.com/u/8799475/images/result.png" width="400" height="100"><br> Which is the same as <code>tlf.z + EPSILON &gt;= tlb.z</code> (equivalent to <code>tlf.z &gt;= tlb.z - EPSILON</code>).<br> In that case, willm1 was actually right. Sorry :)</p>
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    1. POcomparing float inequality (in python)
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    1. COnicely answered. In my own code I ended up doing `math.fabs(tlf.z-tlb.z) < 0.000001`
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    2. COThank you. In that case you're checking for similarity only.
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    3. COquite right, I wrote that forgetting the original question; for `>=` I'd just subtract *half* the fudge factor from the rhs
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