Mathematica 9 is now available
Student Support Forum
Student Support Forum: 'Do I Dot product?' topicStudent Support Forum > General > "Do I Dot product?"

< Previous CommentHelp | Reply To Comment | Reply To Topic
Author Comment/Response
Forum Moderator
email me
09/19/06 06:00am

Look at the Dimensions of you matrix and recall how matrix dimensions are refered to in general mathematics, i.e. n X m. From what you write, I am guessing that you have a flat list such as

In[]:= Dimensions[{1,2,3}]
Out[]= {3}

Now consider:

In[]:= a = {{1, 2, 3}}
Out[]= {{1, 2, 3}}

In[]:= Dimensions[a]
Out[]= {1,3}

In[] := aT = Transpose[a]
Out[]= {{1}, {2}, {3}}

In[]:= Dimensions[aT]
Out[]= {3,1}

These dimensions match the standard requirement for dot products:

Look at the "shape":

In[]:= MatrixForm[a]

1 2 3

In[]:= MatrixForm[aT]




Now the Dot product:

In[]:= a . aT

Out[]= {{14}}

URL: ,

Subject (listing for 'Do I Dot product?')
Author Date Posted
Do I Dot product? Prashanth 09/17/06 4:47pm
Correcting my question Prashanth 09/18/06 10:17pm
Re: Do I Dot product? Bob 09/19/06 02:32am
Re: Do I Dot product? Forum Modera... 09/19/06 06:00am
< Previous CommentHelp | Reply To Comment | Reply To Topic