Initial data commit

Task/Matrix-multiplication/C/matrix-multiplication.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+
+#define MAT_ELEM(rows,cols,r,c) (r*cols+c)
+
+//Improve performance by assuming output matrices do not overlap with
+//input matrices. If this is C++, use the __restrict extension instead
+#ifdef __cplusplus
+    typedef double * const __restrict MAT_OUT_t;
+#else
+    typedef double * const restrict MAT_OUT_t;
+#endif
+typedef const double * const MAT_IN_t;
+
+static inline void mat_mult(
+    const int m,
+    const int n,
+    const int p,
+    MAT_IN_t a,
+    MAT_IN_t b,
+    MAT_OUT_t c)
+{
+    for (int row=0; row<m; row++) {
+        for (int col=0; col<p; col++) {
+            c[MAT_ELEM(m,p,row,col)] = 0;
+            for (int i=0; i<n; i++) {
+                c[MAT_ELEM(m,p,row,col)] += a[MAT_ELEM(m,n,row,i)]*b[MAT_ELEM(n,p,i,col)];
+            }
+        }
+    }
+}
+
+static inline void mat_show(
+    const int m,
+    const int p,
+    MAT_IN_t a)
+{
+    for (int row=0; row<m;row++) {
+        for (int col=0; col<p;col++) {
+            printf("\t%7.3f", a[MAT_ELEM(m,p,row,col)]);
+        }
+        putchar('\n');
+    }
+}
+
+int main(void)
+{
+    double a[4*4] = {1, 1,   1,   1,
+                     2, 4,   8,  16,
+                     3, 9,  27,  81,
+                     4, 16, 64, 256};
+
+    double b[4*3] = {    4.0,   -3.0,  4.0/3,
+                     -13.0/3, 19.0/4, -7.0/3,
+                       3.0/2,   -2.0,  7.0/6,
+                      -1.0/6,  1.0/4, -1.0/6};
+
+    double c[4*3] = {0};
+
+    mat_mult(4,4,3,a,b,c);
+    mat_show(4,3,c);
+    return 0;
+}