lab5

Lab5/vectorangles.c

+#include<stdio.h>
+#include<math.h>
+
+double cosine(int i, int k);
+
+
+double angle;//the angle
+int i,//matrix row, vector nr
+		j,//matrix column, vector coordinate
+		k,//target vector nr
+		matrix[4][3] = {
+		{ 1, 4, 6},
+		{ 2, -3, 1},
+		{ 3, 5, 0},
+		{ 3, 1, -3}
+	};
+	
+int main(){
+	for(i = 0; i < 3; i++){
+		for(k = i + 1; k < 4; k++){
+				angle = acos(cosine( i, k));
+				printf("%lf\n", angle);
+		}
+	}
+	return 0;
+}
+
+double cosine(int i, int k){
+	double dotProd = 0,
+		length_i = 0,
+		length_k = 0;
+	for(j = 0; j < 3; j++){
+		dotProd = dotProd + matrix[i][j]*matrix[k][j];
+		length_i = length_i + pow(matrix[i][j], 2);
+		length_k = length_k + pow(matrix[k][j], 2);
+	}
+	return(dotProd / (sqrt(length_i) * sqrt(length_k)));
+}