title: libjpeg jpeg_write_coefficients
body: <p>I have created my own DCT calculation.</p>
  
  <p>How do I use <code>jpeg_write_coefficients</code> to write my 64 DCT values into JPEG file using <code>jpeg_write_coefficients</code> (it needs <code>jvirt_barray_ptr * coef_arrays</code>)?</p>
  
  <p>How do I create this?</p>