Sum of squares

From Rosetta Code
Revision as of 15:44, 30 January 2008 by rosettacode>Skim (→‎{{header|Perl}}: Add version with map use.)
Task
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).

BASIC

Compiler: QuickBasic 4.5

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);
...

Perl

The computation can be written as a loop.

sub sum_of_squares {
  $sum = 0;
  foreach (@_) {
    $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