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  1. PO
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    <p>The z coordinate of your function is computed in this line:</p> <pre><code> ILArray&lt;float&gt; z = ILMath.meshgrid(R * R, R, y); </code></pre> <p>Since meshgrid is actually used to create the X and Y coordinates for 2 dimensional function evaluation, only the R * R result goes into z. After that line, x,y and z look as follows: </p> <pre><code>x &lt;Single&gt; [5,5] [0]: 0,00000 1,25000 2,50000 3,75000 5,00000 [1]: 0,00000 1,25000 2,50000 3,75000 5,00000 [2]: 0,00000 1,25000 2,50000 3,75000 5,00000 [3]: 0,00000 1,25000 2,50000 3,75000 5,00000 [4]: 0,00000 1,25000 2,50000 3,75000 5,00000 y &lt;Single&gt; [5,5] [0]: 0,00000 0,00000 0,00000 0,00000 0,00000 [1]: 1,25000 1,25000 1,25000 1,25000 1,25000 [2]: 2,50000 2,50000 2,50000 2,50000 2,50000 [3]: 3,75000 3,75000 3,75000 3,75000 3,75000 [4]: 5,00000 5,00000 5,00000 5,00000 5,00000 z &lt;Single&gt; [5,5] [0]: 0,00000 1,56250 6,25000 14,06250 25,00000 [1]: 0,00000 1,56250 6,25000 14,06250 25,00000 [2]: 0,00000 1,56250 6,25000 14,06250 25,00000 [3]: 0,00000 1,56250 6,25000 14,06250 25,00000 [4]: 0,00000 1,56250 6,25000 14,06250 25,00000 </code></pre> <p>Obviously, z does only depend on x, which gets clear by the resulting surface: </p> <p><img src="https://i.stack.imgur.com/qmXlp.png" alt="Surface"></p> <p>So, the value of z would be: x * x. Or for your specific example: </p> <pre><code>x=2.2, y=1.6 z =4.84 </code></pre> <p>Edit: In case the underlying function is not known, you could either </p> <ul> <li>try to learn that function (using ridge_regression() or pinv()), or </li> <li>interpolate from the data of the neighboring grid points. </li> </ul> <p>There is currently no corresponding function (like 'interp2') in ILNumerics. However, in your case - where only one single point needs to be interpolated (?), one can find the neighboring grid points and use one of the common interpolation methods. </p> <p><strong>Edit</strong>: With the release of the <a href="http://ilnumerics.net/ilnumerics-interpolation-toolbox.html" rel="nofollow noreferrer">interpolation toolbox</a> things became significantly easier. You can now interpolate in any dimension in high speed and with a single line.</p>
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    1. POInterpolate 3d surface ilnumerics
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    1. USHaymo Kutschbach
    1. USHaymo Kutschbach
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    1. POInterpolate 3d surface ilnumerics
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    1. COThanks for the explanation.. In my example I assumed to know the relation for the z coordinate. But actually I "only" have a set of points represented in x,y,z coordinates. This points should be interpolated with a surface, which should provide the z coordinate at any point on the surface...
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    2. COHey Haymo, I have set of points - something like 25 points. Out of these points I d like to calculate a surface, where all points have to be on the surface. So with the interpolated surface in hand, it should be possible to calculate the z coordinate between those "control points". Is there any function or method, which determines a surface out of some given points??
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    3. COYou need a function which generates a mesh from the given points. A common mesh generator is delaunay triangulation: http://en.wikipedia.org/wiki/Delaunay_triangulation There is currently no such function provided by the ILNumerics core package.
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      1. USHaymo Kutschbach
 

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