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klaus.joehnk
Germany
3 Posts |
 Posted - 03/08/2001 : 12:00:15 PM
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(Using Origin 6.0 patch 4)
Trying to grid a randomly spaced xyz dataset with prescribed distance (number of columns/rows according to range of x and y columns) produces useless results. The range used internally to grid the data does not correspond to the range in the data.
To show the effect try the following example:
Generate Matrix of size col=10 row=14, set the values of x-first=0, y-first=0, x-last=9,y-last=13. Now set matrix values to lets say i+j (or any other value).
Convert this matrix to xyz-worksheet: Edit - Convert to worksheet - xyz columns.
The error can be seen when converting this worksheet back to matrix.
Select z column and: Edit - Convert to matrix - random xyz
Choose col=10 and row=14 (the original values) and ...
The values will be different from the original matrix.
Miraculously the dimension of the newly created matrix is now changed to y-last=14 (this should be 13), athough the range of values in the worksheet is only up to 13?!
Trying this conversion game (matrix to worksheet and back to matrix) with different dimensions (or simply change the x-last and y-last values to 10 and 14 and everything works fine) shows that such a change in the internally choosen range does occur only sporadic. But what are the conditions?.
Since I need the gridded matrix values with a prescribed distance between grid points it would be fantastic if the gridding dialog in Origin would allow not only to set the number of columns and rows but the distances between grid points!
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Gridding random xyz data - wrong algorithm?
