now version controlled.

1 files changed, 53 insertions, 0 deletions

diff --git a/matrixmul.c b/matrixmul.c
new file mode 100644
index 0000000..c2da272
--- /dev/null
+++ b/matrixmul.c
@@ -0,0 +1,53 @@
+#include <u.h>
+#include <libc.h>
+
+typedef double Matrix[4][4];
+
+void
+mulm(Matrix a, Matrix b)
+{
+	int i, j, k;
+	Matrix r;
+
+	for(i = 0; i < 4; i++)
+		for(j = 0; j < 4; j++){
+			r[i][j] = 0;
+			for(k = 0; k < 4; k++)
+				r[i][j] += a[i][k]*b[k][j];
+		}
+	for(i = 0; i < 4; i++)
+		for(j = 0; j < 4; j++)
+			a[i][j] = r[i][j];
+}
+
+void
+printm(Matrix m)
+{
+	int i, j;
+
+	for(i = 0; i < 4; i++){
+		for(j = 0; j < 4; j++)
+			print("%g\t", m[i][j]);
+		print("\n");
+	}
+}
+
+void
+main()
+{
+	Matrix m1 = {
+		1, 2, -1, 0,
+		2, 0, 1, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0
+	};
+	Matrix m2 = {
+		3, 1, 0, 0,
+		0, -1, 0, 0,
+		-2, 3, 0, 0,
+		0, 0, 0, 0
+	};
+	mulm(m1, m2);
+	printm(m1);
+	exits(0);
+}