Problems "vector"

Consider an implementation of n-dimensional vectors using the structure

typedef struct {int size; double* data;} vector;

1. Implement a set of functions to deal with these vectors. The declarations must be kept in the header file vector.h,

   #ifndef HAVE_VECTOR_H /* for multiple includes */
   #define HAVE_VECTOR_H
   
   typedef struct {int size; double* data;} vector;
   
   vector* vector_alloc       (int n);     /* allocates memory for size-n vector */
   void    vector_free        (vector* v);                      /* frees memory */
   void    vector_set         (vector* v, int i, double value); /* v_i ← value */;
   double  vector_get         (vector* v, int i);              /* returns v_i */
   double  vector_dot_product (vector* u, vector* v);   /* returns dot-product */
   
   /* optional */
   void vector_print    (char* s, vector* v);    /* prints s and then vector */
   void vector_set_zero (vector* v);             /* all elements ← 0 */
   int  vector_equal    (vector* a, vector* b); /* 1, if equal, 0 otherwise */
   void vector_add      (vector* a, vector* b); /* a_i ← a_i + b_i */
   void vector_sub      (vector* a, vector* b); /* a_i ← a_i - b_i */
   void vector_scale    (vector* a, double x);   /* a_i ← x*a_i     */
   /* */
   
   #endif
   

   The implementations of the functions must be in the file vector.c. You should #include"vector.h" in vector.c to allow the compiler to check the declarations. Like this,

   #include<stdio.h>
   #include<assert.h>
   #include"vector.h"
   
   vector* vector_alloc(int n){
     vector* v = malloc(sizeof(vector));
     (*v).size = n;
     (*v).data = malloc(n*sizeof(double));
     if( v==NULL ) fprintf(stderr,"error in vector_alloc\n");
     return v;
   }
   
   void vector_free(vector* v){ free(v->data); free(v);} /* v->data is identical to (*v).data */
   void vector_set(vector* v, int i, double value){
   	assert( 0 <= i && i < (*v).size )
   	(*v).data[i]=value;
   }
   double vector_get(vector* v, int i){
   	assert( 0 <= i && i < (*v).size )
   	return (*v).data[i];
   }
   /* ... */
   

2. Implement a main function that tests your functions, for example,

   #include "vector.h"
   #include "stdio.h"
   #include "stdlib.h"
   #define RND (double)rand()/RAND_MAX
   
   int main()
   {
   	int n = 5;
   
   	printf("\nmain: testing vector_alloc ...\n");
   	vector *v = vector_alloc(n);
   	if (v == NULL) printf("test failed\n");
   	else printf("test passed\n");
   
   	printf("\nmain: testing vector_set and vector_get ...\n");
   	double value = RND;
   	int i = n / 2;
   	vector_set(v, i, value);
   	double vi = vector_get(v, i);
   	if (double_equal(vi, value)) printf("test passed\n");
   	else printf("test failed\n");
   
   	printf("\nmain: testing vector_add ...\n");
   	vector *a = vector_alloc(n);
   	vector *b = vector_alloc(n);
   	vector *c = vector_alloc(n);
   	for (int i = 0; i < n; i++) {
   		double x = RND, y = RND;
   		vector_set(a, i, x);
   		vector_set(b, i, y);
   		vector_set(c, i, x + y);
   	}
   	vector_add(a, b);
   	vector_print("a+b should   = ", c);
   	vector_print("a+b actually = ", a);
   
   	if (vector_equal(c, a)) printf("test passed\n");
   	else printf("test failed\n");
   
   	vector_free(v);
   	vector_free(a);
   	vector_free(b);
   	vector_free(c);
   
   	return 0;
   }