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<?xml version="1.0" encoding="UTF-8"?>
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<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:ns5="http://www.w3.org/1999/xhtml" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:id="eval_cshep2d" xml:lang="en">
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<refname>eval_cshep2d</refname>
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<refpurpose>bidimensional cubic shepard interpolation
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<title>Calling Sequence</title>
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<synopsis>[zp [,dzpdx, dzpdy [,d2zpdxx,d2zpdxy,d2zpdyy]]] = eval_cshep2d(xp, yp, tl_coef)</synopsis>
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<title>Arguments</title>
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<para>two real vectors (or matrices) of the same size</para>
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<para>a tlist scilab structure (of type cshep2d) defining a cubic
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Shepard interpolation function (named <literal>S</literal> in the
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vector (or matrix) of the same size than <literal>xp</literal>
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and <literal>yp</literal>, evaluation of the interpolant
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<literal>S</literal> at these points
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<term>dzpdx,dzpdy</term>
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<para>vectors (or matrices) of the same size than
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<literal>xp</literal> and <literal>yp</literal>, evaluation of the
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first derivatives of <literal>S</literal> at these points
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<term>d2zpdxx,d2zpdxy,d2zpdyy</term>
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<para>vectors (or matrices) of the same size than
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<literal>xp</literal> and <literal>yp</literal>, evaluation of the
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second derivatives of <literal>S</literal> at these points
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<title>Description</title>
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<para>This is the evaluation routine for cubic Shepard interpolation
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function computed with <link linkend="cshep2d">cshep2d</link>, that is
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<imagedata align="center" fileref="../mml/eval_cshep2d_equation1.mml"/>
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The interpolant <emphasis>S</emphasis> is C2 (twice continuously
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differentiable) but is also extended by zero for
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<emphasis>(x,y)</emphasis> far enough the interpolation points. This leads
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to a discontinuity in a region far outside the interpolation points, and
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so, is not cumbersome in practice (in a general manner, evaluation outside
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interpolation points (i.e. extrapolation) leads to very inacurate
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<title>Examples</title>
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<programlisting role="example"><![CDATA[
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<refname>eval_cshep2d</refname>
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<refpurpose>bidimensional cubic shepard interpolation
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<title>Calling Sequence</title>
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<synopsis>[zp [,dzpdx, dzpdy [,d2zpdxx,d2zpdxy,d2zpdyy]]] = eval_cshep2d(xp, yp, tl_coef)</synopsis>
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<title>Arguments</title>
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<para>two real vectors (or matrices) of the same size</para>
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<para>a tlist scilab structure (of type cshep2d) defining a cubic
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Shepard interpolation function (named <literal>S</literal> in the
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vector (or matrix) of the same size than <literal>xp</literal>
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and <literal>yp</literal>, evaluation of the interpolant
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<literal>S</literal> at these points
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<term>dzpdx,dzpdy</term>
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<para>vectors (or matrices) of the same size than
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<literal>xp</literal> and <literal>yp</literal>, evaluation of the
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first derivatives of <literal>S</literal> at these points
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<term>d2zpdxx,d2zpdxy,d2zpdyy</term>
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<para>vectors (or matrices) of the same size than
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<literal>xp</literal> and <literal>yp</literal>, evaluation of the
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second derivatives of <literal>S</literal> at these points
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<title>Description</title>
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<para>This is the evaluation routine for cubic Shepard interpolation
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function computed with <link linkend="cshep2d">cshep2d</link>, that is
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<imagedata align="center" fileref="../mml/eval_cshep2d_equation1.mml"/>
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The interpolant <emphasis>S</emphasis> is C2 (twice continuously
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differentiable) but is also extended by zero for
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<emphasis>(x,y)</emphasis> far enough the interpolation points. This leads
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to a discontinuity in a region far outside the interpolation points, and
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so, is not cumbersome in practice (in a general manner, evaluation outside
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interpolation points (i.e. extrapolation) leads to very inacurate
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<title>Examples</title>
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<programlisting role="example"><![CDATA[
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// see example section of cshep2d
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// this example shows the behavior far from the interpolation points ...
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legends(["extrapolation region","interpolation region"],[2 3],1)
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]]></programlisting>
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<refsection role="see also">
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<title>See Also</title>
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<simplelist type="inline">
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<link linkend="cshep2d">cshep2d</link>
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<title>History</title>
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<revnumber>5.4.0</revnumber>
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<revremark>previously, imaginary part of input arguments were implicitly ignored.</revremark>
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<refsection role="see also">
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<title>See Also</title>
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<simplelist type="inline">
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<link linkend="cshep2d">cshep2d</link>
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<title>History</title>
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<revnumber>5.4.0</revnumber>
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<revremark>previously, imaginary part of input arguments were implicitly ignored.</revremark>