Re: MatrixForm affects values instead of only printing

*To*: mathgroup at smc.vnet.net*Subject*: [mg100318] Re: [mg100298] MatrixForm affects values instead of only printing*From*: "A. B." <functionalcoatings at gmail.com>*Date*: Mon, 1 Jun 2009 07:05:48 -0400 (EDT)

The same holds for TableForm. I have already noticed this. It seems a bit strange, given that "TableForm (MatrixForm) acts as a "wrapper", which affects printing, but not evaluation." In[194]:= list1 = {{1, 2, 3, 4}, {5, 6, 7, 8}} Out[194]= {{1, 2, 3, 4}, {5, 6, 7, 8}} In[195]:= Part[list1, All, 2] Out[195]= {2, 6} And... In[196]:= list1 = {{1, 2, 3, 4}, {5, 6, 7, 8}} // TableForm 1 2 3 4 5 6 7 8 Part[list1, All, 2] 5 6 7 8 A.B. > Here is the example: > > test1={-3, 7, 5} > test1[[3]] > > returns the list and 5 as expected; > > test2={-3, 7, 5}//MatrixForm > test2[[3]] > > returns a column vector and error: "part 3 of blah blah doesn't exist". The > actual list itself is test2[[1]]. To get the right 3rd element I have to do: > > test2[[1,3]] > > which returns 5 as expected. > > > The problem is MatrixForm is NOT supposed to change the expression it is > applied on according to the manual. Is that a bug or there's logical > explanation? >