2 files changed, 168 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index ae2159d..0bf9d87 100644
--- a/Makefile
+++ b/Makefile
@@ -5,11 +5,14 @@ PREFIX = /usr/local
 
 .PHONY: all install
 
-all: temperaturUmrechner
+all: temperaturUmrechner matrixMult
 
 install:
         mkdir -p $(PREFIX)/bin
-        install -m 0755 -t $(PREFIX)/bin temperaturUmrechner
+        install -m 0755 -t $(PREFIX)/bin temperaturUmrechner matrixMult
 
 temperaterUmrechner:
         $(CC) $(INCLUDES) $(CCFLAGS) -o temperaturUmrechner temperaturUmrechner.c
+
+matrixMult:
+        $(CC) $(INCLUDES) $(CCFLAGS) -o matrixMult matrixMult.c
diff --git a/matrixMult.c b/matrixMult.c
new file mode 100644
index 0000000..8e19dac
--- /dev/null
+++ b/matrixMult.c
@@ -0,0 +1,163 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <getopt.h>
+#include <time.h>
+
+#define RANDOM_SEED time(NULL)
+
+void printUsage()
+{
+  fprintf(stderr, "usage: matrixMult -n <INT> -m <INT> -p <INT> [-h]\n"
+          "  Generate random matrices of sizes n*m, m*p and multiply them\n"
+          "  \n"
+          "  n and m need to be nonzero\n"
+          );
+}
+
+void generateMatrix(int *matrix, unsigned int height, unsigned int width)
+{
+  for (int n = 0; n < height; n++)
+    {
+      for (int m = 0; m < width; m++)
+        {
+          matrix[n * width + m] = rand() % 100;
+        }
+    }
+}
+
+void matrixMultiply(int *m1, int *m2, int *res, unsigned int n, unsigned int m, unsigned int p)
+{
+  for (int i = 0; i < n; i++)
+    {
+      for (int j = 0; j < p; j++)
+        {
+          res[i * p + j] = 0;
+          for (int r = 0; r < m; r++)
+            res[i * p + j] += m1[i * m + r] * m2[r * p + j];
+        }
+    }
+}
+
+void main(int argc, char* argv[])
+{
+  int c;
+  unsigned int n = 0;
+  unsigned int m = 0;
+  unsigned int p = 0;
+
+  int *m1;
+  int *m2;
+  int *r;
+  
+  while((c = getopt(argc, argv, "n:m:p:")) != -1)
+    {
+      switch (c)
+        {
+        case 'n':
+          sscanf(optarg, "%u", &n);
+          break;
+        case 'm':
+          sscanf(optarg, "%u", &m);
+          break;
+        case 'p':
+          sscanf(optarg, "%u", &p);
+          break;
+        case 'h':
+          printUsage();
+          exit(0);
+          break;
+        default:
+          printUsage();
+          exit(2);
+        }
+    }
+
+  if (n == 0)
+    fprintf(stderr, "n is zero\n");
+  if (m == 0)
+    fprintf(stderr, "m is zero\n");
+  if (p == 0)
+    fprintf(stderr, "p is zero\n");
+
+  if (n == 0 || m == 0 || p == 0)
+    {
+      printUsage();
+      exit(2);
+    }
+
+  m1 = malloc(sizeof(int) * n * m);
+  m2 = malloc(sizeof(int) * m * p);
+  r = malloc(sizeof(int) * n * p);
+
+  srand(RANDOM_SEED);
+  generateMatrix(m1, n, m);
+  generateMatrix(m2, m, p);
+
+  matrixMultiply(m1, m2, r, n, m, p);
+
+  for (int h = 0; h < (n > m ? n : m); h++)
+    {
+      if (h < n)
+        {
+          printf("(");
+          for (int w = 0; w < m; w++)
+            {
+              printf(" %5d", m1[h * n + w]);
+            }
+          printf(" )");
+        }
+      else
+        {
+          printf("   ");
+          for (int w = 0; w < m; w++)
+            printf(" %5s", "");
+        }
+
+      if (h == 0)
+        printf(" * ");
+      else
+        printf("   ");
+
+      if (h < m)
+        {
+          printf("(");
+          for (int w = 0; w < p; w++)
+            {
+              printf(" %5d", m2[h * p + w]);
+            }
+          printf(" )");
+        }
+      else
+        {
+          printf("   ");
+          for (int w = 0; w < p; w++)
+            printf(" %5s", "");
+        }
+
+      if (h == 0)
+        printf(" = ");
+      else
+        printf("   ");
+
+      if (h < n)
+        {
+          printf("(");
+          for (int w = 0; w < p; w++)
+            {
+              printf(" %5d", r[h * p + w]);
+            }
+          printf(" )");
+        }
+      else
+        {
+          printf("   ");
+          for (int w = 0; w < p; w++)
+            printf(" %5s", "");
+        }
+      
+      printf("\n");
+    }
+
+  free(m1); free(m2); free(r);
+}