Sum of squares
You are encouraged to solve this task according to the task description, using any language you may know.
Write a program to find the sum of squares of a numeric vector. The program should work on a zero-length vector (with an answer of 0).
ALGOL 68
The computation can be written as a loop.
main1:(
PROC sum of squares = ([]REAL argv)REAL:(
REAL sum := 0;
FOR i FROM LWB argv TO UPB argv DO
sum +:= argv[i]**2
OD;
sum
);
printf(($xg(0)l$,sum of squares([]REAL(3, 1, 4, 1, 5, 9))));
)
Output:
133
Another implementation could define a procedure (PROC) or operator (OP) called map.
main2:(
[]REAL data = (3, 1, 4, 1, 5, 9);
PROC map = ( PROC(REAL)REAL func, []REAL argv)REAL:
( REAL out:=0; FOR i FROM LWB argv TO UPB argv DO out:=func(argv[i]) OD; out);
REAL sum := 0;
printf(($xg(0)l$, map ( ((REAL argv)REAL: sum +:= argv ** 2), data) ));
PRIO MAP = 5; # the same priority as the operators <, ≤, ≥, & > maybe... #
OP MAP = ( PROC(REAL)REAL func, []REAL argv)REAL:
( REAL out:=0; FOR i FROM LWB argv TO UPB argv DO out:=func(argv[i]) OD; out);
sum := 0;
printf(($xg(0)l$, ((REAL argv)REAL: sum +:= argv ** 2) MAP data ))
)
Output:
133 133
BASIC
Assume the numbers are in a DIM called a.
sum = 0 FOR I = LBOUND(a) TO UBOUND(a) sum = sum + a(I) ^ 2 NEXT I PRINT "The sum of squares is: " + sum
IDL
print,total(array^2)
J
ss=: +/ @: *:
That is, sum composed with square. The verb also works on higher-ranked arrays. For example:
ss 3 1 4 1 5 9 133 ss $0 NB. $0 is a zero-length vector 0 x=: 20 4 ?@$ 0 NB. a 20-by-4 table of random (0,1) numbers ss x 9.09516 5.19512 5.84173 6.6916
The computation can also be written as a loop. It is shown here for comparison only and is highly non-preferred compared to the version above.
ss1=: 3 : 0
z=. 0
for_i. i.#y do. z=. z+*:i{y end.
)
ss1 3 1 4 1 5 9
133
ss1 $0
0
ss1 x
9.09516 5.19512 5.84173 6.6916
Java
Assume the numbers are in a double array called "nums".
...
double sum = 0;
for(double a : nums){
sum+= a * a;
}
System.out.println("The sum of the squares is: " + sum);
...
OCaml
List.fold_left (fun sum a -> sum + a * a) 0 ints
List.fold_left (fun sum a -> sum +. a *. a) 0. floats
Perl
The computation can be written as a loop.
sub sum_of_squares {
$sum = 0;
foreach (@_) {
$sum += $_ * $_;
}
return $sum;
}
print sum_of_squares(3, 1, 4, 1, 5, 9), "\n";
Output:
133
Other implementation with map use.
@data = qw(3 1 4 1 5 9);
$sum = 0;
map { $sum += $_ ** 2 } @data;
print "$sum\n";
Output:
133