fixed extract commands instructions for tar.gz archive

git-svn-id: https://gforge.sci.utah.edu/svn/nektar/trunk@3101 305cdda6-5ce1-45b3-a98d-dfc68c8b3305

docs/html/compile_osx.html

@@ -142,7 +142,7 @@ generator system. We require version 2.8 or greater.  To check your currently in
 	      If you do not have CMake installed, or the version is too old, then you can build it from source.
                <ol>
               <li>In <em>ThirdParty/</em>, extract the cmake-2.8.0.tar.gz archive with 
-<div class="code"><pre>tar -xjvf cmake-2.8.0.tar.gz</pre></div></li>
+<div class="code"><pre>tar -xzvf cmake-2.8.0.tar.gz</pre></div></li>
 
               <li>Change to the <em>cmake-2.8.0/</em> directory, and type
 <div class="code"><pre>./configure</pre></div> 
@@ -306,7 +306,7 @@ wish
                 <ol>
                     
                     <li>
-                      In <em>ThirdParty/</em>, extract the fftw-3.2.2.tar.gz archive with <div class="code"><pre>tar -xjvf  fftw-3.2.2.tar.gz</pre></div> This will create the directory <em>fftw-3.2.2/</em>.
+                      In <em>ThirdParty/</em>, extract the fftw-3.2.2.tar.gz archive with <div class="code"><pre>tar -xzvf  fftw-3.2.2.tar.gz</pre></div> This will create the directory <em>fftw-3.2.2/</em>.
                     </li>
                     
                     <li>