title: R - difference in last decimal place in different R versions - predict and loess functions
body: <p>I noticed differences in the last digit of decimal numbers in two different R versions.</p>
  <p>I noticed it when using the following code</p>
  <pre><code>predict(loess(x ~ y, z))
  </code></pre>
  <p>The content of my x, y and z variables is the same in both versions. So that can't be the cause.</p>
  <p>These are the types of difference that I see. Notice that there's always a difference in the last digit:</p>
  <pre><code>&lt; 52603 1.94277696545303e-05
  &gt; 52603 1.94277696545304e-05
  
  &lt; 52608 2.03530763978453e-05
  &gt; 52608 2.03530763978454e-05
  </code></pre>
  <p>I have already checked the following things:</p>
  <ul>
  <li>the example code from the loess function R page (<a href="https://www.rdocumentation.org/packages/stats/versions/3.6.2/topics/loess" rel="nofollow noreferrer">https://www.rdocumentation.org/packages/stats/versions/3.6.2/topics/loess</a>). No differences occur there between the two versions</li>
  <li>.Machine output is the same for both R versions</li>
  </ul>
  <p>What could be the cause of this? Or does anybody have suggestions on what to check next to find out the cause of this discrepancy?</p>
  <p>These are the sessionInfo() results of my two R versions</p>
  <pre><code>&gt; sessionInfo()
  R version 3.6.1 (2019-07-05)
  Platform: x86_64-redhat-linux-gnu (64-bit)
  Running under: CentOS Linux 8 (Core)
  
  Matrix products: default
  BLAS/LAPACK: /usr/lib64/R/lib/libRblas.so
  
  locale:
   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
   [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
   [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
   [9] LC_ADDRESS=C               LC_TELEPHONE=C
  [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base
  
  other attached packages:
  [1] optparse_1.6.4
  
  loaded via a namespace (and not attached):
  [1] compiler_3.6.1 tools_3.6.1    getopt_1.20.3
  
  
  &gt; sessionInfo()
  R version 3.4.3 (2017-11-30)
  Platform: x86_64-pc-linux-gnu (64-bit)
  Running under: openSUSE 12.2 (Mantis) (x86_64)
  
  Matrix products: default
  BLAS: /nexus/software/R/Rapp/lib64/R/lib/libRblas.so
  LAPACK: /nexus/software/R/Rapp/lib64/R/lib/libRlapack.so
  
  locale:
   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
   [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
   [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
   [9] LC_ADDRESS=C               LC_TELEPHONE=C
  [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base
  
  other attached packages:
  [1] optparse_1.6.0
  
  loaded via a namespace (and not attached):
  [1] compiler_3.4.3 getopt_1.20.2
  </code></pre>