How to write values of function to file?

Question

For example, say I wanted to plot Sin(x) like this:

Plot[Sin[x],{x,0,2 Pi}]

But instead of plotting to a graph, I want to now tabulate the values of Sin[x] to a data file. How do I achieve this?

EDIT: Sorry I wasn't clear enough, I mean plot the x values in one column and the y values in the second column

Answer 1

First create your points, running from 0 to 2 Pi at intervals of 0.01.

points = Table[{x,Sin[x]}, {x, Range[0, 2 \[Pi], .01]}];

You can plot them with:

ListLinePlot[points]

And export them to a csv file with:

Export["points.csv", points]

Answer 2

You can select the points from the plot and write it to file with Export:

pl = Plot[Sin[x], {x, 0, 2 Pi}];

The Points are arguments to a Line directive in the Plot function:

Position[pl, Line]

output is: {{1, 1, 3, 2, 0}} the zero is the Head of the Line directive, the points are the argument:

points = pl[[1, 1, 3, 2, 1]];

Alternatively you can also produce the {x,y} pairs directly:

points = Table[Sin[x], {x, 0, 2 Pi, 0.1}];

Now I use export to write it all to a file

Export[< output.file >, points, "Table"]

Please note, that there is a typo in your code. You should use square brackets to give function argumens: Sin[x] instead of Sin(x)

Edit:

To get {x,y} pairs from a list of x-positions you can for instance use:

xypairs = {#, Sin[#]} & /@ points

/@ is a shorthand notation for Map. To calculate it directly in the Table command replace Sin[x] by {x,Sin[x]}.

Here is another method to get the points directly from the plot using EvaluationMonitor:

{pl, points} = 
  Reap[Plot[Sin[x], {x, 0, 2 Pi}, 
    EvaluationMonitor :> Sow[{x, Sin[x]}]]];

Answer 3

This is to show some of Mathematica's other features.

create a list of x values:

x = Range[0, 2 Pi, 0.1];

create a list of y values:

y = Sin @ x;

(Sin is Listable; if it were not you would use Map: Sin /@ x. Also see Function.)

Put them together:

data = {x, y}\[Transpose];

The Transpose symbol is entered EsctrEsc.

Export data in whatever format you desire, e.g.:

ExportString["datafile.txt", data, "Table"]