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Re: Export a vector

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  • Subject: [mg108829] Re: Export a vector
  • From: Bill Rowe <readnews at>
  • Date: Fri, 2 Apr 2010 05:20:42 -0500 (EST)

On 4/1/10 at 6:00 AM, sagittarius5962 at (nt) wrote:

>I have a question on how to export an array from a loop with
>several iterating varibles: for example:

>equation= some equation!

>I can give the loop a name like L=Do[....] and write
>Export["file.xls",L] but what I get is the matrix with dimensions of

If you actually tried to Export as you described above and got
what you stated it would be very surprising. The return value
from Do is Null unless a specific Return is used per the
documentation. Setting L = Do[...] and getting what you report
would be a bug.

>can I only export bet[i] which is a vector within the loop to a

The first thing you need to realize is bet[i] is not a vector
within the loop. None of your code creates a vector or a matrix
(more properly in Mathematica a list).

The notation bet[i] is the function evaluated with the value i.
And since your code does not define values for bet with single
arguments, bet[i] will return unevaluated.

For example, I can define values for f[i,j] as follows:

In[16]:= Table[f[i, j] = RandomInteger[100], {i, 3}, {j, 3}]

Out[16]= {{35, 5, 19}, {22, 87, 75}, {98, 27, 46}}

and to demonstrate f has been assigned values for specific i,j

In[17]:= f[1, 1]

Out[17]= 35

but note,

In[18]:= f[1]

Out[18]= f[1]

since f has not be defined for a single argument. For something
that behaves like a matrix, I would do:

In[19]:= g = Table[RandomInteger[100], {3}, {3}]

Out[19]= {{70, 1, 89}, {17, 92, 49}, {43, 24, 72}}

Now I can extract the first row by:

In[20]:= g[[1]]

Out[20]= {70,1,89}

or the first column by:

In[21]:= g[[All, 1]]

Out[21]= {70,17,43}

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