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Version:
4.4.5.dfsg-3ubuntu2 ▾
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<HTML>
<HEAD>
<TITLE>2D interpolation</TITLE>
</HEAD>
<BODY bgcolor="#FFFFFF" fgcolor="#000000">
<P><A NAME="bivinterp"></A>
<font size="+3" color="green"><B>2D interpolation</B></font></P>
<P>
<TABLE border="1" cols="2" frame="box" rules="all" width="572">
<TR>
<TD width="15%" valign="top"><B>Syntax</B>:</TD>
<TD width="85%"><CODE>
w = BIVINTERP(x,y,z,u,v)</CODE>
</TD></TR>
</table></p>
<p>
This function interpolates, from values of the function given at input grid
points in an <i>x</i>-<i>y</i> plane and for a given set of points in the plane, the values
of a single-valued bivariate function <i>z = z(x,y)</i>. The method is based on a
piece-wise function composed of a set of bicubic polynomials in <i>x</i> and <i>y</i>.
Each polynomial is applicable to a rectangle of the input grid in the <i>x</i>-<i>y</i>
plane. Each polynomial is determined locally.</P>
<P>
The first two input parameters are vectors. Vector <code>x</code> contains the <i>x</i>-coordinates
of the input grid points, in ascending order. Vector <code>y</code> contains the
<i>y</i>-coordinates of the input grid points, in ascending order. Both <code>x</code> and
<code>y</code> must be monotonically increasing. The third parameter is a matrix, <code>z</code>,
which contains the values of the function at the input grid points, <code>z[i][j]</code> is the
data value at <code>(x[i],y[j])</code>. The last two parameters are vectors. Vector
<code>u</code> contains the <i>x</i>-coordinates of the desired
points, and vector <code>v</code> contains the <i>y</i>-coordinates of the desired points. Vectors
<code>u</code> and <code>v</code> must have the same number of elements. The output is a vector,
<code>w</code>, containing the interpolated values, <code>w[i]</code> is the interpolated value at the
location <code>(u[i],v[i])</code>.</P>
<P>
Algorithm derived from an article by Hiroshi Akima, <b>Communications of the ACM</b>, volume 17, number 1,
January 1974, pp. 26-31.</P>
<P>
<a href="interpolateS05.htm"><img align="top" border="0" src="../shadow_left.gif">
<font size="+1" color="olive">SPLINTERP function</font></a>
</P>
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