Ошибка линковки: Linker command failed with exit code 1 - C (СИ)

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
#include "lss_19_07.h"
 
int d, e;
 
int strncmp(const char *s1, const char *s2, size_t n);
 
int search(char *argv[], const char *param, int argc);
 
int main(int argc, char *argv[]) {
    d = e = 0;
    
    const char *in, *out, *in_, *out_;
    in = "/Users/doublench/Desktop/zxczxc/zxczxc/lss_19_07_in.txt";
    out = "/Users/doublench/Desktop/zxczxc/zxczxc/lss_19_07_out.txt";
    
    if (argc > 1) {
        if (argv[1][0] == '-' && argc > 5) {
            perror("Too much parametеrs...");
            exit(2);
        }
        
        if (argv[1][0] != '-' && argc > 7) {
            in_ = argv[1];
            out_ = argv[2];
            perror("Too much parametеrs...");
            exit(2);
        }
    }
    
    if (argc > 1) {
        int i;
        if (argv[1][0] == '-')
            i = 1;
        else
            i = 3;
        
        for (; i < argc; ++i) {
            if (strncmp(argv[i], "-d", 2) == 0 || strncmp(argv[i], "-e", 2) == 0 ||
                strncmp(argv[i], "-p", 2) == 0 || strncmp(argv[i], "-t", 2) == 0 ||
                strncmp(argv[i], "-h", 2) == 0 || strncmp(argv[i], "-?", 2) == 0) {
            } else {
                perror("Unknown parameter/s...");
                exit(3);
            }
        }
    }
    
    if (argc > 2) {
        int count, i;
        count = i = 0;
        
        char params[4][2] = {{'d', '0'}, {'e', '0'}, {'p', '0'}, {'t', '0'}};
        
        if (argv[1][0] == '-')
            i = 1;
        else
            i = 3;

        for (; i < argc; ++i) {
            int j;
            for (j = 0; j < 4; ++j) {
                if (argv[i][1] == 'h' || argv[i][1] == '?')
                    count = 1;
                if (argv[i][1] == params[j][0] && params[j][1] != '0')
                    count = 1;
                if (argv[i][1] == params[j][0] && params[j][1] == '0')
                    params[j][1] = '1';
            }
        }
        if (count) {
            perror("Incorrect set of parameters...");
            exit(4);
        }
    }
    
    if (strncmp(argv[1], "-h", 2) == 0 || strncmp(argv[1], "-?", 2) == 0) {
        printf("Usage: lss [input_file_name] [output_file_name] [options]\n");
        printf("Where options include:\n");
        printf(" -d    print debug messages [default OFF]\n");
        printf(" -e    print errors [default OFF]\n");
        printf(" -p    print matrix [default OFF]\n");
        printf(" -t    print execution time [default OFF]\n");
        printf(" -h,-? print help\n");
        exit(0);
    }
    
    if (search(argv, "-e", argc) == 0)
        e = 1;
    
    FILE *fin;
    if (argv[1][0] == '-')
        fin = fopen(in, "r");
    else
        fin = fopen(in_, "r");
    
    if (fin == NULL) {
        if (e == 1)
            perror("File open error...");
        exit(5);
    }
    
    int n;
    if (fscanf(fin, "%d", &n) != 1) {
        if (e == 1)
            perror("Read error...");
        exit(6);
    }
    
    if (n <= 0) {
        if (e == 1)
            perror("Value of n is less or equal 0...");
        exit(7);
    }
    
    double *A, *B, *X;
    if ((A = (double *) malloc(n * n * sizeof(double))) == NULL) {
        if (e == 1)
            perror("Memory allocation error...");
        exit(8);
    }
    
    if ((B = (double *) malloc(n * sizeof(double))) == NULL) {
        if (e == 1)
            perror("Memory allocation error...");
        exit(8);
    }
    if ((X = (double *) malloc(n * sizeof(double))) == NULL) {
        if (e == 1)
            perror("Memory allocation error...");
        exit(8);
    }
    
    int i;
    for (i = 0; i < n * n; ++i)
        if (fscanf(fin, "%lf", &A[i]) != 1) {
            if (e == 1)
                perror("Read error...");
            exit(6);
        }
    
    if (search(argv, "-p", argc) == 0) {
        printf("Matrix A:\n");
        int k;
        for (k = 1; k <= n * n; ++k) {
            printf("%lf ", A[k - 1]);
            if (k % n == 0)
                printf("\n");
        }
        printf("\n");
    }
    
    for (i = 0; i < n; ++i)
        if (fscanf(fin, "%lf", &B[i]) != 1) {
            if (e == 1)
                perror("Read error...");
            exit(6);
        }
    
    if (fclose(fin)) {
        if (e == 1)
            perror("Close error...");
        exit(9);
    }
    
    if (search(argv, "-d", argc) == 0)
        d = 1;
    
    clock_t time;
    if ((time = clock()) == -1) {
        if (e == 1)
            perror("Time is unavailable on this system...");
        exit(10);
    }
    
    if (lss_19_07(n, A, B, X) == -1) {
        FILE *fout;
        
        if (argv[1][0] == '-')
            fout = fopen(out, "wb");
        else
            fout = fopen(out_, "wb");
        
        if (fout == NULL) {
            if (e == 1)
                perror("File open error...");
            exit(5);
        }
        
        if (fprintf(fout, "") < 0) {
            if (e == 1)
                perror("Write error...");
            
            exit(11);
        }
        // TODO: -1 ?
        return -1;
    }
    
    time = clock() - time;
    
    if (search(argv, "-t", argc) == 0)
        printf("Time: %f\n", (double) time);
    
    FILE *fout;
    if (argv[1][0] == '-')
        fout = fopen(out, "wb");
    else
        fout = fopen(out_, "wb");
    
    if (fout == NULL) {
        if (e == 1)
            perror("File open error...");
        exit(5);
    }
    
    if (fprintf(fout, "%d\n", n) < 0) {
        if (e == 1)
            perror("Write error...");
        exit(11);
    }
    
    for (i = 0; i < n; ++i)
        if (fprintf(fout, "%1.9lf\n", X[i]) < 0) {
            if (e == 1)
                perror("Write error...");
            exit(11);
        }
    
    if (fclose(fout)) {
        if (e == 1)
            perror("Close error...");
        exit(9);
    }
    
    free(A);
    free(B);
    free(X);
    
    return 0;
}
 
int strncmp(const char *s1, const char *s2, size_t n) {
    for (; n > 0; s1++, s2++, --n)
        if (*s1 != *s2)
            return ((*(unsigned char *) s1 < *(unsigned char *) s2) ? -1 : +1);
        else if (*s1 == '\0')
            return 0;
    return 0;
}
 
int search(char *argv[], const char *param, int argc) {
    int i;
    
    for (i = 1; i < argc; ++i)
        if (strncmp(argv[i], param, 2) == 0)
            return 0;
    return -1;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
#include "lss_19_07.h"
 
extern int d, e;
 
int lss_19_07(int n, double *A, double *B, double *X) {
  int i, j, k;
  double summ;
  
  clock_t time;
  if ((time = clock()) == -1) {
    if (e == 1)
      perror("Time is unavailable on this system...");
    exit(10);
  }
  
  if (d == 1) {
    printf("Solving l[i][1]...(i = 1, ..., %d)\n", n);
    clock_t time1 = clock() - time;
    printf("Solving done...\n");
    printf("Current time: %f\n\n", (double)time1);
  }
  
  if (A[0] == 0)
    return -1;
    
  if (d == 1)
    printf("Solving u[1][k]...(k = 2, ..., %d)\n", n);
    
  for (k = 1; k < n; ++k)
    A[k] = A[k] / A[0];
    
  if (d == 1) {
    clock_t time2 = clock() - time;
    printf("Solving done...\n");
    printf("Current time: %f\n\n", (double)time2);
  }
  
  for (i = 1; i < n; ++i) {
    if (d == 1)
      printf("Solving l[i][k]...(1<k<=i, i,k = 2, ..., %d)\n", n);
      
    for (k = 1; k <= i; ++k) {
      summ = 0.0;
      for (j = 0; j <= k - 1; ++j)
        summ += A[i * n + j] * A[j * n + k];
      A[i * n + k] = A[i * n + k] - summ;
      if (i == k && A[i * n + k] == 0)
        return -1;
    }
    
    if (d == 1) {
      clock_t time3 = clock() - time;
      printf("Solving done...\n");
      printf("Current time: %f\n\n", (double)time3);
    }
    
    if (d == 1)
      printf("Solving u[i][k]...(k>i>1, i,k = 2, ..., %d)\n", n);
      
    for (k = i + 1; k < n; ++k) {
      summ = 0.0;
      for (j = 0; j <= i - 1; ++j)
        summ += A[i * n + j] * A[j * n + k];
      A[i * n + k] = (A[i * n + k] - summ) / A[i * n + i];
    }
    
    if (d == 1) {
      clock_t time4 = clock() - time;
      printf("Solving done...\n");
      printf("Current time: %f\n\n", (double)time4);
    }
  }
  
  // TODO: проверка несовместимости системы
  if (d == 1)
    printf("Solving Ly=B...\n");
    
  X[0] = B[0] / A[0];
  for (i = 1; i < n; ++i) {
    summ = 0.0;
    for (j = 0; j < i; ++j)
      summ += A[i * n + j] * X[j];
    X[i] = (B[i] - summ) / A[i * n + i];
  }
  
  if (d == 1) {
    clock_t time5 = clock() - time;
    printf("Solving done...\n");
    printf("Current time: %f\n\n", (double)time5);
  }
  
  if (d == 1)
    printf("Solving Ux=y...\n");
    
  for (i = n - 2; i >= 0; --i) {
    summ = 0.0;
    for (j = n - 1; j >= i + 1; --j)
      summ += X[j] * A[i * n + j];
    X[i] = X[i] - summ;
  }
  
  if (d == 1) {
    clock_t time6 = clock() - time;
    printf("Solving done...\n");
    printf("Current time: %f\n\n", (double)time6);
}
 
  return 0;
}

#ifndef INC_07_LSS_19_07_H
#define INC_07_LSS_19_07_H
 
int lss_19_07(int n, double *A, double *B, double *X);
 
#endif // INC_07_LSS_19_07_H