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Xsim-3D development... I could use some math help
Xsim-3D development... I could use some math help
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Old 24th January 2018, 03:41 AM   #21
nc535 is offline nc535
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Originally Posted by bwaslo View Post
Los Angeles?
line arrays

re' which I expanded your example to 24 drivers and everything was fine; then added a driver and got access violation at address 00515BC1

Last edited by nc535; 24th January 2018 at 03:44 AM.
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Old 24th January 2018, 03:49 AM   #22
bwaslo is offline bwaslo  United States
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Xsim-3D development... I could use some math help
line arrays... should've seen that.

Can you zip up the file (before adding the crashing step) and send or post it?
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Old 24th January 2018, 04:02 AM   #23
nc535 is offline nc535
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here you go
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Old 24th January 2018, 05:14 AM   #24
bwaslo is offline bwaslo  United States
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Xsim-3D development... I could use some math help
Havent got to your file, but wondering --is this a LA youve built? If, so great test case to compare with reality!
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Old 24th January 2018, 06:00 AM   #25
AllenB is offline AllenB  Australia
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Originally Posted by bwaslo View Post
the phase component
You mention you are pre-diffraction at this point. Couldn't you use an absolute distance value for phase?
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Old 24th January 2018, 06:58 AM   #26
DPH is offline DPH  United States
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Originally Posted by bwaslo View Post
Can you explain? I know of Sinc interpolation for connecting sample points without adding new HF data, but is there such a thing for complex values?
I probably was a little too quick to pull the trigger on my response WRT complex interpolation. In what I read as follow-up, the trend I'm noticing is that folks will split the arrays into their real and imaginary components (or polar, take your pick) and do the interpolation of the two arrays separately.

Not sure how badly that would screw up magnitudes, though.

E.g python - Interpolate whole arrays of complex numbers - Stack Overflow albeit this discussion is for Numpy, same concept.

E.g. (2) This is how Matlab's baked in interpolation does it, too http://www.mathworks.com/help/matlab...html#btw0gu1-1
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Last edited by DPH; 24th January 2018 at 07:02 AM.
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Old 24th January 2018, 12:38 PM   #27
nc535 is offline nc535
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Originally Posted by bwaslo View Post
Havent got to your file, but wondering --is this a LA youve built? If, so great test case to compare with reality!
It's the same driver as @wesayso. Spacing need to be tweked to match
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Old 24th January 2018, 06:36 PM   #28
bwaslo is offline bwaslo  United States
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Xsim-3D development... I could use some math help
Quote:
Originally Posted by DPH View Post
I probably was a little too quick to pull the trigger on my response WRT complex interpolation. In what I read as follow-up, the trend I'm noticing is that folks will split the arrays into their real and imaginary components (or polar, take your pick) and do the interpolation of the two arrays separately.

Not sure how badly that would screw up magnitudes, though.

E.g python - Interpolate whole arrays of complex numbers - Stack Overflow albeit this discussion is for Numpy, same concept.

E.g. (2) This is how Matlab's baked in interpolation does it, too 1-D data interpolation (table lookup) - MATLAB interp1
DPH, thanks.

Actually, I already do something like that for interpolation over frequency. I used a "constrained spline" curve fit to map from one set of frequency points to another. In the sim I always work with the same set of frequency points, so when data is read in from any-old FRD file, the first thing that happens is to map it to my working frequency list. I usually interpolate real and imaginary (separately), since that sidesteps the issue of unwrapping phase being somewhat error prone. But I guess there's no reason such an interpolation wouldn't work for points spaced geometrically. But it still doesn't solve my issue of how to combine data taken at horizontal offsets with data taken at vertical offsets.

My test case (a circular piston, where I can calculate response vs an angle "theta" relative to the disk's normal vector) lets me calculate a usable value, and also I can calculate responses from vertical and horizontal offset angles-only values separately so I can check how well various combining approaches work (ideally, the result would be the same using the overall 'theta' value.

I haven't gotten too far into it today (other matters call) but it occurred to me this morning that I should perhaps convert the measured data arrays so the they are mapped, instead of in Horizontal and Vertical angles, into something more "circularly" oriented, see diagram below -
Xsim-3D development... I could use some math help-thetaalpha-png
IOW, define an orientation in terms of the angle "Theta" (as before for circular disks) and another angle (call it "Alpha", as its one of the few Greek symbols I recognize both name and symbol for!). I don't remember the terminology for this coordinate system (is this the "spherical"?). Anyway, I'm looking at ways to combine response values in terms of these two angles.... might still not help the basic problems of how to combine. But if I use a basic interpolation between two sets on the same Theta angle (not on H and V directly), but interpolate on the Alpha angle rather than some other parameter, I should be able to get it so interpolating between two data points taken where they differ only in Alpha I can get the same complex result yields the same complex result also. I think. (This is where I would've done well to have spent more time in math classes and less in circuit theory classes )
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Last edited by bwaslo; 24th January 2018 at 06:42 PM.
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Old 24th January 2018, 06:37 PM   #29
bwaslo is offline bwaslo  United States
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Xsim-3D development... I could use some math help
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Originally Posted by nc535 View Post
It's the same driver as @wesayso. Spacing need to be tweked to match
Thanks, I'll drop wesayso a PM and see if he can send me some measured data.
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Old 24th January 2018, 06:42 PM   #30
gedlee is offline gedlee  United States
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Originally Posted by bwaslo View Post
Is there such a thing as a spline curve-fit for an array of complex values??
Sure there is, I do it all the time. All you have to do actually is to take any real interpolation algorithm and make the variables complex. In FORTRAN this is trivial, in other languages not so much since only FORTRAN has a complex data type and keeps track of all the complexities for you. The only "gotcha" is that if you ever need to multiply two complex numbers then "usually" you have to multiple one as a conjugate.

I have a FORTRAN routine that will do this that I could send you.
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