Does Mathematica have an equivalent to Matlab's linspace? I want to make a list with "start", "stop" and "number of points". What is the neatest way of doing this?
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2 Answers
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There was an update for Array, not done to the end. The method below does not work for earlier versions even though that Array is
New in 1 | Last modified in 4
Moreover WRI forgot to update docs for error messages: Array::plen - the first example gives no error in V9.
V9
Array[# &, n, {start, stop}]
Array[# &, 10, {-1, 1}]
{-1, -(7/9), -(5/9), -(1/3), -(1/9), 1/9, 1/3, 5/9, 7/9, 1}
V<9
ClearAll[linespace];
linespace[s_, f_, 1] := (f + s)/2
linespace[s_, f_, n_] := Range[s, f, (f - s)/(n - 1)]
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$\begingroup$ Nice, this one I´ll crib shamelessly :D $\endgroup$ Nov 29, 2013 at 12:29
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$\begingroup$ I've written
Range[s, f, (f - s)/(n - 1)]so many times that my fingers run across the keyboard on their own $\endgroup$ Nov 29, 2013 at 20:32 -
1$\begingroup$ Daaamn... I should've answered this question instead of the dupe. I answered the exact same question 3 months ago with the same answer and got only 2 votes :P $\endgroup$– rm -rf ♦Dec 1, 2013 at 17:22
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You could use table... unless I am missing something really basic. Speed, maybe? Edited to consider the special case as suggested by Kuba.
linspace[start_, stop_, n_:100] := Table[x, {x, start, stop, (stop - start)/(n - 1)}]
linspace[start_, stop_, 1] := Mean[{start,stop}]
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$\begingroup$ Ah, ok. My procedures are written with the implicit disclaimer "this will help you aim at your foot, it's up to you not to pull the trigger". Well, it can be overloaded to consider the special case. $\endgroup$– PeltioNov 29, 2013 at 18:24
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$\begingroup$ I like this disclaimer :) but notice that I'm not reminding about negative numbers, strings etc. but about little function deficiency. $\endgroup$– Kuba ♦Nov 29, 2013 at 18:36
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$\begingroup$ I certainly appreciate feedback. So, basically, this special case could arise within some automated task that could compute the number of points and come up with the special, and apparently useless case n=1. Before writing my post I had a look at the web documentation for linspace for MATLAB and this special case is not mentioned. Actually, I see now this cens.ioc.ee/local/man/matlab/techdoc/ref/linspace.html is the first page that came up but it appears it is not on Mathworks servers. So my bad for not checking it thoroughly. $\endgroup$– PeltioNov 29, 2013 at 18:41
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$\begingroup$ it seems there is no good answer :)
n=1seems useless but on the other hand, why not? $\endgroup$– Kuba ♦Nov 29, 2013 at 19:02