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Re: Hi

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116251] Re: Hi
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Tue, 8 Feb 2011 05:07:14 -0500 (EST)

On 2/7/11 at 6:05 AM, isableng at gmail.com (Isabella Blengini) wrote:

>Hi I have a problem. I created a column vector of 100 rows, let's
>say a[100,1]. Each row corresponds to the value of my function in
>each unit of time. I would like to plot this vector. I should get a
>function that has a value a(1,1) at time 1, a(2,1) at time 2 and so
>on... Any suggestions???

To start, try actually creating what Mathematica recognizes as a
vector. Note

In[1]:= test = Array[a, 10]

Out[1]= {a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10]}

In[2]:= VectorQ[a]

Out[2]= False

In[3]:= VectorQ[test]

Out[3]= True

In Mathematica, the syntax a[100,1] is interpreted as the
function a evaluated with arguments 100 and 1. It is definitely
not a vector as the above demonstrates.

VectorQ[expr] returns true whenever expr is a one-dimensional
list. And when VectorQ[expr] is true, you can plot expr using
ListPlot. For example the following will plot the sin function
for one cycle

test = Sin[Range[100]*(Pi/50)];
ListPlot[test]



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