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      <title>Standard B-Spline Format</title>
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      <div class="title_topic1" id="xps10_pagetitle">Standard B-Spline Format</div>
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      <p class="para_topic">The following is the standard format of B-spline commands for the Cutter Location(CL) file:</p>
      <p class="para_topic"><img align="bottom" src="graphics/bspline_foAt01.gif" border="0"></p>
      <p class="para_topic">The following are some conventions/properties:</p>
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         <li>
            <p class="para_item">The allowed p (order) are 2,3, or 4. B-spline of order 2 represents linear segments, which allows the consolidation of GOTO/ command into Spline format.</p>
         </li>
         <li>
            <p class="para_item">The start point, i.e. the zeroth control point, of the spline is the last programmed position before the NURBS/ command and is not repeated. The weight of the start point is always 1.0. The zeroth control point is not included when counting the number of control points, N.</p>
         </li>
         <li>
            <p class="para_item">The first p knot parameters are always 0.0 and are always omitted, such that  <img align="bottom" src="graphics/bspline_foeq02.gif" border="0"> is the (p+1)th knot parameter. The last p knot parameters are always the same, so we can ignore the last (p-1) knot parameters. Hence the total number of independent t values are (N-p+2).
            </p>
         </li>
         <li>
            <p class="para_item">If N-p+2 is too big, the knot vector may be too long to fit into one line. In such case the KNOT/ command can be repeated to accommodate all t parameters.</p>
         </li>
         <li>
            <p class="para_item">The tool-axis (i,j,k) can be interpolated by B-splines. The tool-axis vector will be omitted for fixed-axis toolpath.</p>
         </li>
         <li>
            <p class="para_item">The feedrate and spindle rate can also be interpolated by B-splines. The format for interpolated feedrate and spindle rate will be proposed later.</p>
         </li>
      </ul>
      <p class="para_topic">For the PTP file, refer to the NX Postprocessing Help. </p>
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