# [Scilab-users] slash (/) help page confusing ?

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## [Scilab-users] slash (/) help page confusing ?

 Hi before scilab6 there was some ambiguity between 1/B=1./B=(1.)/B  since 1. = 1 for floating point real numbers. We can see that this problem is solved now : --> B=1:3  B  =    1.   2.   3. --> 1./B  ans  =    1.   0.5   0.3333333 --> 1/B  ans  =    0.0714286    0.1428571    0.2142857 but in the help page it is written that "X=A/B is the solution of X*B=A" this false for  A=1  and B=1:3  as you can see : --> B*(1/B)  // =1 !!!!  ans  =    1. --> (1/B)*B  //  should be 1 ?  ans  =    0.0714286   0.1428571   0.2142857    0.1428571   0.2857143   0.4285714    0.2142857   0.4285714   0.6428571 but this is true for general matrix --> A=[1 2 ; 3 4]  A  =    1.   2.    3.   4. --> B=[4 5 ; 6 7]  B  =    4.   5.    6.   7. --> B*(A/B) // sould be A ?  ans  =    17.5  -8.5    25.5  -12.5 --> (A/B)*B // =A  ans  =    1.   2.    3.   4. this looks confusing ? Best regards, Philippe _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: slash (/) help page confusing ?

 Le 30/08/2018 à 09:32, philippe a écrit : > Hi > > before scilab6 there was some ambiguity between 1/B=1./B=(1.)/B  since > 1. = 1 for floating point real numbers. We can see that this problem is > solved now : > > > --> B=1:3 >   B  = > >     1.   2.   3. > > > --> 1./B >   ans  = > >     1.   0.5   0.3333333 > > > --> 1/B >   ans  = > >     0.0714286 >     0.1428571 >     0.2142857 > > but in the help page it is written that "X=A/B is the solution of X*B=A" > this false for  A=1  and B=1:3  as you can see : > > > --> B*(1/B)  // =1 !!!! >   ans  = > >     1. > > > --> (1/B)*B  //  should be 1 ? >   ans  = > >     0.0714286   0.1428571   0.2142857 >     0.1428571   0.2857143   0.4285714 >     0.2142857   0.4285714   0.6428571 > > but this is true for general matrix > > --> A=[1 2 ; 3 4] >   A  = > >     1.   2. >     3.   4. > > > --> B=[4 5 ; 6 7] >   B  = > >     4.   5. >     6.   7. > > > --> B*(A/B) // sould be A ? >   ans  = > >     17.5  -8.5 >     25.5  -12.5 > > > --> (A/B)*B // =A >   ans  = > >     1.   2. >     3.   4. > > > this looks confusing ? No. For square A, B, invertible B, "A/B" means "A*inv(B)", hence B*(A/B)=B*A*inv(B) cannot be equal to A (matrix product is not commutative) S. > > Best regards, > Philippe > > _______________________________________________ > users mailing list > [hidden email] > https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users-- Stéphane Mottelet Ingénieur de recherche EA 4297 Transformations Intégrées de la Matière Renouvelable Département Génie des Procédés Industriels Sorbonne Universités - Université de Technologie de Compiègne CS 60319, 60203 Compiègne cedex Tel : +33(0)344234688 http://www.utc.fr/~mottelet_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: slash (/) help page confusing ?

 Le 30/08/2018 à 09:42, Stéphane Mottelet a écrit : > Le 30/08/2018 à 09:32, philippe a écrit : >>   >> [...] >> but in the help page it is written that "X=A/B is the solution of X*B=A" > > > For square A, B, invertible B, "A/B" means "A*inv(B)", hence > B*(A/B)=B*A*inv(B) cannot be equal to A (matrix product is not commutative) I know this but for non-square matrices scilab use the opposite convention, IMHO it's confusing, and the case of a scalar in the help page doesn't mention this change. the help page should be updated. Best regards, Philippe _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: slash (/) help page confusing ?

 Le 30/08/2018 à 10:03, philippe a écrit : > Le 30/08/2018 à 09:42, Stéphane Mottelet a écrit : >> Le 30/08/2018 à 09:32, philippe a écrit : >>>   >>> [...] >>> but in the help page it is written that "X=A/B is the solution of X*B=A" >> >> For square A, B, invertible B, "A/B" means "A*inv(B)", hence >> B*(A/B)=B*A*inv(B) cannot be equal to A (matrix product is not commutative) > I know this but for non-square matrices scilab use the opposite > convention, OK. To me, the / operator does not correctly check the compatibility of respective dimensions of A and B. The statements: A=1; B=[1 2 3]; X=A/B should raise an error because A and B must have the same number of columns if the equality X*B=A has to make sense. With the following statements A=1; B=[1 2 3]'; X=A/B X*B we get a coherent result: --> X=A/B   X  =     0.   0.   0.3333333 --> X*B   ans  =     1. S. > IMHO it's confusing, and the case of a scalar in the help > page doesn't mention this change. the help page should be updated. > > Best regards, > > Philippe > > _______________________________________________ > users mailing list > [hidden email] > https://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users-- Stéphane Mottelet Ingénieur de recherche EA 4297 Transformations Intégrées de la Matière Renouvelable Département Génie des Procédés Industriels Sorbonne Universités - Université de Technologie de Compiègne CS 60319, 60203 Compiègne cedex Tel : +33(0)344234688 http://www.utc.fr/~mottelet_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: slash (/) help page confusing ?

 Le 30/08/2018 à 10:22, Stéphane Mottelet a écrit : > Le 30/08/2018 à 10:03, philippe a écrit : >> Le 30/08/2018 à 09:42, Stéphane Mottelet a écrit : >>> Le 30/08/2018 à 09:32, philippe a écrit : >>>>   [...] >>>> but in the help page it is written that "X=A/B is the solution of >>>> X*B=A" >>> >>> For square A, B, invertible B, "A/B" means "A*inv(B)", hence >>> B*(A/B)=B*A*inv(B) cannot be equal to A (matrix product is not >>> commutative) >> I know this but for non-square matrices scilab use the opposite >> convention, > OK. To me, the / operator does not correctly check the compatibility > of respective dimensions of A and B. The statements: > > A=1; > B=[1 2 3]; > X=A/B > > should raise an error because A and B must have the same number of > columns if the equality X*B=A has to make sense. > > With the following statements > > A=1; > B=[1 2 3]'; > X=A/B > X*B > > we get a coherent result: > > --> X=A/B >  X  = > >    0.   0.   0.3333333 > > --> X*B >  ans  = > >    1. > > S. in Matlab, dimensions are correctly checked:  >> 1/[1 2 3] Error using  / Matrix dimensions must agree. Bug created @ http://bugzilla.scilab.org/show_bug.cgi?id=15746S. >> IMHO it's confusing, and the case of a scalar in the help >> page doesn't mention this change. the help page should be updated. >> >> Best regards, >> >> Philippe >> >> _______________________________________________ >> users mailing list >> [hidden email] >> https://antispam.utc.fr/proxy/2/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users  >> > > -- Stéphane Mottelet Ingénieur de recherche EA 4297 Transformations Intégrées de la Matière Renouvelable Département Génie des Procédés Industriels Sorbonne Universités - Université de Technologie de Compiègne CS 60319, 60203 Compiègne cedex Tel : +33(0)344234688 http://www.utc.fr/~mottelet_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: slash (/) help page confusing ?

 Le 30/08/2018 à 10:34, Stéphane Mottelet a écrit : > in Matlab, dimensions are correctly checked: > >>> 1/[1 2 3] > Error using  / > Matrix dimensions must agree. > > Bug created @ http://bugzilla.scilab.org/show_bug.cgi?id=15746this looks more coherent ! For a column vector A the behavior of 1/A 1./A is now coherent. Philippe _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## [Scilab-users] Any chance SciLab 6 operational again under macOS 10.14?

 System Version: macOS 10.14 (18A377a)   Kernel Version: Darwin 18.0.0 Darwin Kernel Version 18.0.0: Wed Aug 22 20:59:21 PDT 2018; root:xnu-4903.201.2~4/RELEASE_X86_64 x86_64 Apple LLVM version 9.1.0 (clang-902.0.39.2) Target: x86_64-apple-darwin18.0.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin Any chance SciLab 6 operational again under macOS 10.14? Heinz _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: Any chance SciLab 6 operational again under macOS 10.14?

 Heinz Nabielek <[hidden email]> a écrit : System Version:        macOS 10.14 (18A377a) Kernel Version:        Darwin 18.0.0 Darwin Kernel Version 18.0.0: Wed Aug 22 20:59:21 PDT 2018; root:xnu-4903.201.2~4/RELEASE_X86_64 x86_64 Apple LLVM version 9.1.0 (clang-902.0.39.2) Target: x86_64-apple-darwin18.0.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin Any chance SciLab 6 operational again under macOS 10.14? Heinz _______________________________________________ users mailing list [hidden email].orghttps://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users Hello, Tonight I installed the latest Mojave beta on a second partition of my Mac Book disk and were able to run Scilab. Here is how I proceeded: 1-The OS has been installed on a new partition without any old data import 2-I installed the command line tools (open a Terminal the type "make" to trigger the download/install) 3-Downloaded the official 6.0.1 for OSX from scilab.org and move the app in /Applications 4-Deleted some libraries bundled by Scilab: \$  rm /Applications/scilab-6.0.1.app/Contents/MacOS/lib/thirdparty/libBLAS.dylib \$  rm /Applications/scilab-6.0.1.app/Contents/MacOS/lib/thirdparty/libz.* 5-Commented out the line  774 in /Applications/scilab-6.0.1.app/Contents/MacOS/bin/scilab                       #fail_macosx_version 6-Launched Scilab from its icon. At first run, you will be asked to install Java 1.6 See the attached screenshot. S. _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users attachment0 (95K) Download Attachment
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## Re: Any chance SciLab 6 operational again under macOS 10.14?

 [hidden email] a écrit : Heinz Nabielek <[hidden email]> a écrit : System Version:        macOS 10.14 (18A377a) Kernel Version:        Darwin 18.0.0 Darwin Kernel Version 18.0.0: Wed Aug 22 20:59:21 PDT 2018; root:xnu-4903.201.2~4/RELEASE_X86_64 x86_64 Apple LLVM version 9.1.0 (clang-902.0.39.2) Target: x86_64-apple-darwin18.0.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin Any chance SciLab 6 operational again under macOS 10.14? Heinz _______________________________________________ users mailing list [hidden email].orghttps://antispam.utc.fr/proxy/1/c3RlcGhhbmUubW90dGVsZXRAdXRjLmZy/lists.scilab.org/mailman/listinfo/users Hello, Tonight I installed the latest Mojave beta on a second partition of my Mac Book disk and were able to run Scilab. Here is how I proceeded: 1-The OS has been installed on a new partition without any old data import 2-I installed the command line tools (open a Terminal the type "make" to trigger the download/install) 3-Downloaded the official 6.0.1 for OSX from scilab.org and move the app in /Applications 4-Deleted some libraries bundled by Scilab: \$  rm /Applications/scilab-6.0.1.app/Contents/MacOS/lib/thirdparty/libBLAS.dylib \$  rm /Applications/scilab-6.0.1.app/Contents/MacOS/lib/thirdparty/libz.* 5-Commented out the line  774 in /Applications/scilab-6.0.1.app/Contents/MacOS/bin/scilab                       #fail_macosx_version   6-Launched Scilab from its icon. At first run, you will be asked to install Java 1.6 See the attached screenshot. S.   I forgot to say something in step 5. Change Line 803 as follows (add 14, the OSX minor version number)                 10|11|12|13|14) S. _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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