Need help with creating a List

• To: mathgroup at yoda.ncsa.uiuc.edu (Mathematica Mailing List)
• Subject: Need help with creating a List
• From: Avi Y. Feldblum <uunet!pruxk!ayf>
• Date: Wed, 22 Aug 90 12:57:13 EDT

I am having some trouble with creating a list for plotting with
ListPlot. As I understand it, what is needed is a list of lists, where
each element of the main list is a list of two values, the x and y
positions to be plotted. In my case, the x values are just a set of
evenly spaced values, while the y values are the difference between some
data I have and a functional form for the data. What I have is:

func[x_] = "some long function"

The data is in a list called "data"

diff[x_] := data[[x]] - func[.05x]

difftable = Table[ {.05i, diff[i]}, {i, Length[data]} ]

My problem is the output of difftable. It looks like:

{{.05, {value1}}, {.01, {value2}}, ....}

What it needs to be for ListPlot to work (I think) is:

{{.05, value1}, {.01, value2}, ....}

I tried to make a test file with a simple func[x_] and just put in some
datapoints, and there it did work. So I'm confused as to when and why
mathematica is giving me {{xval1,yval1},{xval2,yval2}, ..} in one case
and {{xval1,{yval1}}, {xval2,{yval2}}, ..} in the other case.

Any ideas or suggestions?

--
Avi Feldblum
ayf at pruxk.att.com   or  avi_feldblum at att.com

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