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I have a multivariate function that I want to map into a triple of variables.

x = {0.01`, 0.11`, 0.21000000000000002`, 0.31000000000000005`, 
   0.41000000000000003`, 0.51`, 0.6100000000000001`, 
   0.7100000000000001`, 0.81`, 0.91`};
y = {1.`, 1.`, 1.`, 1.`, 1.`, 0.9804148800744802`, 
   0.8196730260718126`, 0.6189620070242443`, 0.40469250572443105`, 
   0.26901189545273474`};
z = {0.8153370522348216`, 0.8853249359665971`, 0.9223317847713025`, 
   0.9559380865485229`, 0.9999999995185327`, 1.`, 1.`, 
   0.9084506972387802`, 0.7345679056105409`, 0.5989011012000781`};
domain = Partition[Flatten[{x, y, z}], 3];

f[x_, y_, z_] := (x + 1.5*y + 1.2*z)/(1 + x);

Map[f, domain]

I want

{f[0.01, 0.11, 0.21], f[0.31, 0.41, 0.51], f[0.61, 0.71, 0.81], 
 f[0.91, 0.815337, 0.885325], f[0.922332, 0.955938, 1.], 
 f[1., 1., 0.908451], f[0.734568, 0.598901, 1.], f[1., 1., 1.], 
 f[1., 0.980415, 0.819673], f[0.618962, 0.404693, 0.269012]}

But for some reason when I Map[f, domain] I get:

{f[{0.01, 0.11, 0.21}], f[{0.31, 0.41, 0.51}], f[{0.61, 0.71, 0.81}], 
 f[{0.91, 0.815337, 0.885325}], f[{0.922332, 0.955938, 1.}], 
 f[{1., 1., 0.908451}], f[{0.734568, 0.598901, 1.}], f[{1., 1., 1.}], 
 f[{1., 0.980415, 0.819673}], f[{0.618962, 0.404693, 0.269012}]}

I have searched the documentation and other posts, but I still cannot figure what is going on with this very simple problem.

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  • 1
    $\begingroup$ Either define f[{x_, y_, z_}]:=...., or do Apply[f, domain, 1] (in short-hand notation: f @@@ domain). $\endgroup$ – corey979 Feb 20 '18 at 17:24
  • $\begingroup$ Would say that looks like to form triplets as mydom=Thread[{x,y,z}] $\endgroup$ – Anxon Pués Feb 20 '18 at 17:30
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    $\begingroup$ Or this domain=Transpose@{x, y, z} $\endgroup$ – OkkesDulgerci Feb 20 '18 at 19:01
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I tested this and work as , I think, you expect 

    x = RandomInteger[{0, 9}, 10];
    y = RandomInteger[{0, 9}, 10];
    z = RandomInteger[{0, 9}, 10];
    mydom = Thread[{x, y, z}];
    Apply[f, mydom, 2]
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  • $\begingroup$ Of course. Thank you so much, @AnxonPues. $\endgroup$ – Laura K Feb 20 '18 at 17:54
  • $\begingroup$ And also thank you for using the RandomInteger to create a better example than mine! $\endgroup$ – Laura K Feb 20 '18 at 18:51
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It is simple. f @@@ domain is all you need.

f @@@ domain

{0.422772, 1.17328, 1.6441, 1.89005, 1.85, 1.49094, 1.27189, 1.81186, 1.85, 1.42995}

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  • $\begingroup$ Of course! Thank you so much, @m_goldberg! $\endgroup$ – Laura K Feb 20 '18 at 18:50

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