title: "fftw.h not found" after installing it in Mac terminal
body: <p>I'm running problem of getting fftw working. I'm on mac and have installed fftw using brew on the terminal.</p>
  
  <pre><code>brew install fftw
  </code></pre>
  
  <p>It gave me a reminder of "Warning: fftw 3.3.8 is already installed and up-to-date" if I put in this install command again. But I cannot call fftw.h in C. It gave me an error of "fftw.h file not found" if I have a line of</p>
  
  <pre><code>#include &lt;fftw.h&gt;
  </code></pre>
  
  <p>I also tried installing directly by</p>
  
  <pre><code>./configure
  make
  make install
  </code></pre>
  
  <p>and ran</p>
  
  <pre><code>make check
  </code></pre>
  
  <p>It told me "FFTW transforms passed basic tests!", but it still didn't work in C.</p>
  
  <p>Any suggestions would be appreciated! </p>