Matrix multiplication: Difference between revisions
Content added Content deleted
m (minor formatting and wording) |
(Ada example) |
||
Line 1: | Line 1: | ||
{{task}}Multiply two Matrices together, they can be of any dimension as long as the number of columns of the first matrix is equal to the number of rows of the second matrix |
{{task}}Multiply two Matrices together, they can be of any dimension as long as the number of columns of the first matrix is equal to the number of rows of the second matrix |
||
=={{header|Ada}}== |
|||
package Matrix_Ops is |
|||
type Matrix is array(Natural range <>, Natural range <>) of Float; |
|||
function "*" (Left, Right : Matrix) return Matrix; |
|||
Dimension_Violation : exception; |
|||
end Matrix_Ops; |
|||
package body Matrix_Ops is |
|||
--------- |
|||
-- "*" -- |
|||
--------- |
|||
function "*" (Left, Right : Matrix) return Matrix is |
|||
Temp : Matrix(Left'Range(1), Right'Range(2)) := (Others =>(Others => 0.0)); |
|||
begin |
|||
if Left'Length(2) /= Right'Length(1) then |
|||
raise Dimension_Violation; |
|||
end if; |
|||
for I in Left'range(1) loop |
|||
for J in Right'range(2) loop |
|||
for K in Left'range(2) loop |
|||
Temp(I,J) := Temp(I,J) + Left(I, K)*Right(K, J); |
|||
end loop; |
|||
end loop; |
|||
end loop; |
|||
return Temp; |
|||
end "*"; |
|||
end Matrix_Ops; |
|||
=={{header|Common Lisp}}== |
=={{header|Common Lisp}}== |
Revision as of 00:29, 10 December 2007
Matrix multiplication
You are encouraged to solve this task according to the task description, using any language you may know.
You are encouraged to solve this task according to the task description, using any language you may know.
Multiply two Matrices together, they can be of any dimension as long as the number of columns of the first matrix is equal to the number of rows of the second matrix
Ada
package Matrix_Ops is type Matrix is array(Natural range <>, Natural range <>) of Float; function "*" (Left, Right : Matrix) return Matrix; Dimension_Violation : exception; end Matrix_Ops;
package body Matrix_Ops is --------- -- "*" -- --------- function "*" (Left, Right : Matrix) return Matrix is Temp : Matrix(Left'Range(1), Right'Range(2)) := (Others =>(Others => 0.0)); begin if Left'Length(2) /= Right'Length(1) then raise Dimension_Violation; end if; for I in Left'range(1) loop for J in Right'range(2) loop for K in Left'range(2) loop Temp(I,J) := Temp(I,J) + Left(I, K)*Right(K, J); end loop; end loop; end loop; return Temp; end "*"; end Matrix_Ops;
Common Lisp
(defun matrix-multiply (a b) (flet ((col (mat i) (mapcar #'(lambda (row) (elt row i)) mat)) (row (mat i) (elt mat i))) (loop for row from 0 below (length a) collect (loop for col from 0 below (length (row b 0)) collect (apply #'+ (mapcar #'* (row a row) (col b col))))))) ;; example use: (matrix-multiply '((1 2) (3 4)) '((-3 -8 3) (-2 1 4)))
SQL
CREATE TABLE a (x integer, y integer, e real); CREATE TABLE b (x integer, y integer, e real); -- test data -- A is a 2x2 matrix INSERT INTO a VALUES(0,0,1); INSERT INTO a VALUES(1,0,2); INSERT INTO a VALUES(0,1,3); INSERT INTO a VALUES(1,1,4); -- B is a 2x3 matrix INSERT INTO b VALUES(0,0,-3); INSERT INTO b VALUES(1,0,-8); INSERT INTO b VALUES(2,0,3); INSERT INTO b VALUES(0,1,-2); INSERT INTO b VALUES(1,1, 1); INSERT INTO b VALUES(2,1,4); -- C is 2x2 * 2x3 so will be a 2x3 matrix SELECT rhs.x, lhs.y, (SELECT sum(a.e*b.e) FROM a, b WHERE a.y = lhs.y AND b.x = rhs.x AND a.x = b.y) INTO TABLE c FROM a AS lhs, b AS rhs WHERE lhs.x = 0 AND rhs.y = 0;