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Bug in Trigrid ? [message #1854]

Thu, 24 March 1994 18:55

hahn
Messages: 108
Registered: November 1993

Senior Member

I found some erroneous data being generated on the boundary
by trigrid when interpolating x,y,z triplets into a matrix.
The problem depends on the system you run IDL on:
When you run the following program on a rs6000 or a pc you
get incorrect results while running on a sun you get
correct results. The problem occurs with version 3.1 and 3.5.1
of IDL (I don't have access to older version).

I assume that triangulate/trigrid is used very much I wonder
if there is a bug in IDL or in my program:

pro ttrig
x = findgen(30) ; generate some artifical data to show problem
y = x
Z = x # y + 200 ; matrix to plot as reference.

surface, z, zrange=[ 0, 1000 ]

; Now pick 30 values randomly choosen to feed into trigrid

seed = 12345
i = 30 * randomu ( seed, 30 )
j = 30 * randomu ( seed, 30 )
a = x(i)
b = y(j)
c = a * b + 200

triangulate, a, b, tr

zmat = trigrid ( a, b, c, tr )

; zmat should be very close the the original matrix Z above
; or am I missing something ???

window, 1 ; open another window for a-b comparison

surface, zmat, zrange=[ 0, 1000 ] ; qed

end

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[Message index]

		Bug in Trigrid ? By: hahn on Thu, 24 March 1994 18:55
		Re: Bug in Trigrid ? By: manizade on Mon, 28 March 1994 07:48

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