If you have a list of numbers
v = {3, 9/2, 4}
the command GCD will not work on a list and returns
{3, 9/2, 4}
but
GCD[3, 9/2, 4]
returns an answer of 1/2 which is correct. How do you 'unlist' a list so that GCD will work with a list?
All the following methods do the trick:
In[504]:= A = {3, 9/2, 4}; GCD @@ A Apply[GCD, A] GCD[A /. List -> Sequence] GCD[Sequence @@ A] Out[505]= 1/2 Out[506]= 1/2 Out[507]= 1/2 Out[508]= 1/2
For some related discussions, see here.
You can apply Sequence[] to turn a list into arguments:
GCD[Apply[Sequence, {3, 9/2, 4}]]
or
GCD[Sequence @@ {3, 9/2, 4}]
Thanks.
Check out
Apply
Applying Functions to Lists
