I guess I don't understand how threading works. Suppose I define a function

f[v__, c__] := v + c;

Here v is intended to be a vector, and c is a scalar::

vec = {a, b, c, d};

f [vec, x]

then yields

{a + x, b + x, c + x, d + x}

Suppose I want to repeat this for a sequence of c's. I would write:

cs = {e, f, g}

Table[ f [vec, cs[[i]] ], {i, Length[cs]}]

I then get

{{a + e, b + e, c + e, d + e}, {a + f, b + f, c + f, d + f}, {a + g,  b + g, c + g, d + g}}

Now I'd like to do this same thing in parallel:

Thread[ f [vec, cs], List, {2}]

My understanding of this statement is that I want to evaluate f [vec, c] for each c contained in {e, f, g}.

Instead what I get is:

Thread::tdlen: Objects of unequal length in {a,b,c,d}+{e,f,g} cannot be combined. >>

I attach a pdf version of my Mathematica session. If anyone can clarify this for me, I would appreciate it. Thanks for reading this.

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