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MathGroup Archive 2003

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Re: Bug in ColorFunctionScaling ???

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39453] Re: Bug in ColorFunctionScaling ???
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Sun, 16 Feb 2003 06:13:56 -0500 (EST)
  • References: <b2fqud$k9q$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Just to be specific about the point made by earlier contributers to this
thread - that what you are seeing is the result of Mathematica clipping the
plot range to what it thinks is significant, and that this can be avoided by
setting PlotRange->All.

With

    dp=ListDensityPlot[matrix];

We have

    PlotRange[dp][[3]]

        {0.,0.000092028}

Which is a very small part of the range of matrix values:

    Through[{Min,Max}[matrix]]

        {6.532730362808272*^-22, 0.9373917995816773}

So every matrix value at or above 0.000092028 gives white and each value,v ,
in {0.,0.000092028} gives GrayLevel[v/0.000092028].
The latter scaling gives more discrimination than you want in the this
range.

This clipping does not occur with BarChart3D because the default setting is
PlotRange -> All.
But it does occur with

    ListPlot3D[matrix];

--
Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565



"Cesar Guerra" <guerra_cesar at yahoo.com> wrote in message
news:b2fqud$k9q$1 at smc.vnet.net...
>
>
> Hi math group
>
> working with the matrix given at the end of this mail I had troubles
trying to visualize it. For instance
>
> ListDensityPlot[matrix]
>
> works too bad as can be seen using a 3D chart
>
> <<Graphics`Graphics3D`
>
> BarChart3D[matrix]
>
> I got the correct density plot when I scaled the matrix elements by hand:
>
> min = Min[matrix];
>
> max = Max[matrix];
>
>
ListDensityPlot[matrix,ColorFunctionScaling->False,ColorFunction->(GrayLevel
[(#-min)/(max-min)]&)];
>
> The question: is it a bug or I lost something in the way? A similar
problem arises with many matrices that I generated in which there are many
numbres close to zero.
>
> Regards.. Cesar,
>
> Well here is the matrix. Sorry because of the horrible format
>
> matrix={{0.024880970532441947`,0.13578975670808227`,0.027812229119535358`,
>
0.0033045651867030673`,0.0003347493056088158`,0.000026302686284994582`,
>
0.00004371748398547436`,0.00003681120741920656`,0.00003087537872290685`,
>
0.00001905600654956626`,0.000011958703618226977`,5.517957585379249`*^-6,
>       1.8928075271017263`*^-6,5.269301156366419`*^-7,
>       6.489638911064354`*^-8},{0.13578975670808227`,0.9373917995816773`,
>       0.19133899349592184`,0.02294180236292207`,0.002146876534122984`,
>
0.00002231000770522592`,0.0001344726022920243`,0.00012287370329599313`,
>
0.00011865976751467771`,0.00008588847348107676`,0.0000650218873670948`,
>
0.00003769993910579926`,0.000017332922552971424`,7.275477707153364`*^-6,
>       1.801352169404378`*^-6},{0.027812229119535358`,0.19133899349592184`,
>       0.03906478452215391`,0.004681738877149381`,0.0004385133576867982`,
>       4.090272132604937`*^-6,0.000027823395408896714`,
>
0.000025374358467023346`,0.00002443091259330744`,0.0000176320249591744`,
>
0.000013309659796768249`,7.69480720132288`*^-6,3.5276710986778535`*^-6,
>
1.47654392225098`*^-6,3.645535247058728`*^-7},{0.0033045651867030673`,
>       0.02294180236292207`,0.004681738877149381`,0.0005797298493723746`,
>
0.000052839536129011784`,4.7226000276470905`*^-7,3.368374620650723`*^-6,
>       3.069745381714908`*^-6,2.952410460102803`*^-6,2.12852330993168`*^-6,
>
1.605032461433652`*^-6,9.269514851713523`*^-7,4.2451346697061517`*^-7,
>
1.7749887062983138`*^-7,4.377821687374563`*^-8},{0.0003347493056088158`,
>
0.002146876534122984`,0.0004385133576867982`,0.000052839536129011784`,
>
9.255816438202384`*^-6,4.1249326083329274`*^-8,3.0266675833749047`*^-7,
>
2.757224026816698`*^-7,2.650178380130713`*^-7,1.9094596136360029`*^-7,
>       1.43896434791398`*^-7,8.305350785567792`*^-8,3.801262097259811`*^-8,
>       1.588429369111028`*^-8,
>       3.915317215838556`*^-9},{0.000026302686284994582`,
>
0.00002231000770522592`,4.090272132604937`*^-6,4.7226000276470905`*^-7,
>
4.1249326083329274`*^-8,3.535859690725517`*^-6,2.1961201225893756`*^-8,
>
2.0000362799666382`*^-8,1.92152398727093`*^-8,1.3838515977742497`*^-8,
>
1.0424076404006913`*^-8,6.0138740883614725`*^-9,2.7512702310528075`*^-9,
>       1.1491658404200648`*^-9,
>       2.831335936719118`*^-10},{0.00004371748398547436`,
>
0.0001344726022920243`,0.000027823395408896714`,3.368374620650723`*^-6,
>
3.0266675833749047`*^-7,2.1961201225893756`*^-8,1.3721693600020958`*^-6,
>
1.2199036050151096`*^-9,1.17158414848564`*^-9,8.434512469918671`*^-10,
>       6.351128550113803`*^-10,3.6627785449735637`*^-10,
>       1.675069186742091`*^-10,6.993998508257666`*^-11,
>       1.7225733012431472`*^-11},{0.00003681120741920656`,
>
0.00012287370329599313`,0.000025374358467023346`,3.069745381714908`*^-6,
>
2.757224026816698`*^-7,2.0000362799666382`*^-8,1.2199036050151096`*^-9,
>
5.794192640789079`*^-7,6.135409523313631`*^-11,4.4155949418835226`*^-11,
>       3.3238340437588365`*^-11,1.916277391009494`*^-11,
>       8.760720928814635`*^-12,3.6567233858746355`*^-12,
>       9.003344351753371`*^-13},{0.00003087537872290685`,
>
0.00011865976751467771`,0.00002443091259330744`,2.952410460102803`*^-6,
>       2.650178380130713`*^-7,1.92152398727093`*^-8,1.17158414848564`*^-9,
>
6.135409523313631`*^-11,2.6403332491754`*^-7,2.0055352842629293`*^-12,
>
1.509195581203532`*^-12,8.698207176501544`*^-13,3.975359904169974`*^-13,
>       1.6587999868150363`*^-13,
>       4.0829224450233844`*^-14},{0.00001905600654956626`,
>
0.00008588847348107676`,0.0000176320249591744`,2.12852330993168`*^-6,
>
1.9094596136360029`*^-7,1.3838515977742497`*^-8,8.434512469918671`*^-10,
>
4.4155949418835226`*^-11,2.0055352842629293`*^-12,7.78759863903862`*^-8,
>       5.953442715856466`*^-14,3.4301675965039096`*^-14,
>       1.567201965631006`*^-14,6.53740694684916`*^-15,
>       1.6085914870370433`*^-15},{0.000011958703618226977`,
>
0.0000650218873670948`,0.000013309659796768249`,1.605032461433652`*^-6,
>
1.43896434791398`*^-7,1.0424076404006913`*^-8,6.351128550113803`*^-10,
>       3.3238340437588365`*^-11,1.509195581203532`*^-12,
>       5.953442715856466`*^-14,2.9305747143573262`*^-8,
>       1.1656559281957215`*^-15,5.323917587243905`*^-16,
>       2.2200368196954134`*^-16,
>       5.4608078423152933`*^-17},{5.517957585379249`*^-6,
>
0.00003769993910579926`,7.69480720132288`*^-6,9.269514851713523`*^-7,
>
8.305350785567792`*^-8,6.0138740883614725`*^-9,3.6627785449735637`*^-10,
>       1.916277391009494`*^-11,8.698207176501544`*^-13,
>
3.4301675965039096`*^-14,1.1656559281957215`*^-15,7.76299670479757`*^-9,
>       1.5221789994509213`*^-17,6.345037635961268`*^-18,
>       1.5602293071790306`*^-18},{1.8928075271017263`*^-6,
>       0.000017332922552971424`,3.5276710986778535`*^-6,
>
4.2451346697061517`*^-7,3.801262097259811`*^-8,2.7512702310528075`*^-9,
>
1.675069186742091`*^-10,8.760720928814635`*^-12,3.975359904169974`*^-13,
>       1.567201965631006`*^-14,5.323917587243905`*^-16,
>       1.5221789994509213`*^-17,1.6163732178696085`*^-9,
>       1.4386200807791453`*^-19,
>
3.530345878524741`*^-20},{5.269301156366419`*^-7,7.275477707153364`*^-6,
>
1.47654392225098`*^-6,1.7749887062983138`*^-7,1.588429369111028`*^-8,
>       1.1491658404200648`*^-9,6.993998508257666`*^-11,
>       3.6567233858746355`*^-12,1.6587999868150363`*^-13,
>
6.53740694684916`*^-15,2.2200368196954134`*^-16,6.345037635961268`*^-18,
>       1.4386200807791453`*^-19,3.740548209112563`*^-10,
>
6.532730362808272`*^-22},{6.489638911064354`*^-8,1.801352169404378`*^-6,
>
3.645535247058728`*^-7,4.377821687374563`*^-8,3.915317215838556`*^-9,
>       2.831335936719118`*^-10,1.7225733012431472`*^-11,
>       9.003344351753371`*^-13,4.0829224450233844`*^-14,
>       1.6085914870370433`*^-15,5.4608078423152933`*^-17,
>       1.5602293071790306`*^-18,3.530345878524741`*^-20,
>       6.532730362808272`*^-22,4.517936598686041`*^-11}}
>
>
>




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