Problems "nvector"

Consider an implementation of n-dimensional vectors using the structure

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

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

   #ifndef HAVE_NVECTOR_H /* for multiple includes */
   
   typedef struct {int size; double* data;} nvector;
   
   nvector* nvector_alloc       (int n);     /* allocates memory for size-n vector */
   void     nvector_free        (nvector* v);                      /* frees memory */
   void     nvector_set         (nvector* v, int i, double value); /* v_i ← value */;
   double   nvector_get         (nvector* v, int i);              /* returns v_i */
   double   nvector_dot_product (nvector* u, nvector* v);   /* returns dot-product */
   
   /* optional */
   void nvector_print    (char* s, nvector* v);    /* prints s and then vector */
   void nvector_set_zero (nvector* v);             /* all elements ← 0 */
   int  nvector_equal    (nvector* a, nvector* b); /* 1, if equal, 0 otherwise */
   void nvector_add      (nvector* a, nvector* b); /* a_i ← a_i + b_i */
   void nvector_sub      (nvector* a, nvector* b); /* a_i ← a_i - b_i */
   void nvector_scale    (nvector* a, double x);   /* a_i ← x*a_i     */
   /* */
   
   #define HAVE_NVECTOR_H
   #endif
   

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

   #include<stdio.h>
   #include"nvector.h"
   
   nvector* nvector_alloc(int n){
     nvector* v = malloc(sizeof(nvector));
     (*v).size = n;
     (*v).data = malloc(n*sizeof(double));
     if( v==NULL ) fprintf(stderr,"error in nvector_alloc\n");
     return v;
   }
   
   void nvector_free(nvector* v){ free(v->data); free(v);}
   
   void nvector_set(nvector* v, int i, double value){ (*v).data[i]=value; }
   
   double nvector_get(nvector* v, int i){return (*v).data[i]; }
   
   /* ... */
   

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

   #include "nvector.h"
   #include "stdio.h"
   #include "stdlib.h"
   #define RND (double)rand()/RAND_MAX
   
   int main()
   {
   	int n = 5;
   
   	printf("\nmain: testing nvector_alloc ...\n");
   	nvector *v = nvector_alloc(n);
   	if (v == NULL) printf("test failed\n");
   	else printf("test passed\n");
   
   	printf("\nmain: testing nvector_set and nvector_get ...\n");
   	double value = RND;
   	int i = n / 2;
   	nvector_set(v, i, value);
   	double vi = nvector_get(v, i);
   	if (double_equal(vi, value)) printf("test passed\n");
   	else printf("test failed\n");
   
   	printf("\nmain: testing nvector_add ...\n");
   	nvector *a = nvector_alloc(n);
   	nvector *b = nvector_alloc(n);
   	nvector *c = nvector_alloc(n);
   	for (int i = 0; i < n; i++) {
   		double x = RND, y = RND;
   		nvector_set(a, i, x);
   		nvector_set(b, i, y);
   		nvector_set(c, i, x + y);
   	}
   	nvector_add(a, b);
   	nvector_print("a+b should   = ", c);
   	nvector_print("a+b actually = ", a);
   
   	if (nvector_equal(c, a)) printf("test passed\n");
   	else printf("test failed\n");
   
   	nvector_free(v);
   	nvector_free(a);
   	nvector_free(b);
   	nvector_free(c);
   
   	return 0;
   }
   

3. (Optional)

   Implement range checking using <assert.h>, for example,

   void nvector_set(nvector* v, int i, double value){
   	assert( 0 <= i && i < (*v).size )
   	(*v).data[i]=value;
   }