C Program to implement Linear regression algorithm.

Posted on November 17, 2011 by Sandeepa Nadahalli

Linear Regression is the predicting the value of one scalar variable(y) using the explanatory another variable(x). Linear regression is represented by the equation Y = a + bX, where X is the explanatory variable and Y is the scalar variable. The slope of the line is b, and a is the intercept. For linear list square modeling, Linear regression is very helpful. Read more about C Programming Language.

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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
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*                      Happy Coding
***********************************************************/



#include "stdio.h"
#include "conio.h"
#include "math.h"
#include "string.h"

float mean(float *a, int n);
void deviation(float *a, float mean, int n, float *d, float *S);

void main() {
 float a[20], b[20], dx[20], dy[20];
 float sy = 0, sx = 0, mean_x = 0, mean_y = 0, sum_xy = 0;
 float corr_coff = 0, reg_coff_xy = 0, reg_coff_yx = 0;
 char type_coff[7];
 int n = 0, i = 0;

 clrscr();

 printf("Enter the value of n: ");
 scanf("%d", &n);
 printf("Enter the values of x and y:n");
 for (i = 0; i < n; i++)
  scanf("%f%f", &a[i], &b[i]);
 mean_x = mean(a, n);
 mean_y = mean(b, n);
 deviation(a, mean_x, n, dx, &sx);
 deviation(b, mean_y, n, dy, &sy);

 for (i = 0; i < n; i++)
  sum_xy = sum_xy + dx[i] * dy[i];
 corr_coff = sum_xy / (n * sx * sy);
 printf("Enter the type of regression coefficient as 'x on y' or 'y on x': ");
 fflush(stdin);
 gets(type_coff);

 if (strcmp(type_coff, "x on y") == 1) {
  reg_coff_xy = corr_coff * (sx / sy);
  printf("nThe value of linear regression coefficient is %f",
    reg_coff_xy);
 } else if (strcmp(type_coff, "y on x") == 1) {
  reg_coff_yx = corr_coff * (sy / sx);
  printf("nThe value of linear regression coefficient is %f",
    reg_coff_yx);
 } else
  printf("nEnter the correct type of regression coefficient.");
 getch();
}

float mean(float *a, int n) {
 float sum = 0, i = 0;
 for (i = 0; i < n; i++)
  sum = sum + a[i];
 sum = sum / n;
 return (sum);
}

void deviation(float *a, float mean, int n, float *d, float *s) {
 float sum = 0, t = 0;
 int i = 0;
 for (i = 0; i < n; i++) {
  d[i] = a[i] - mean;
  t = d[i] * d[i];
  sum = sum + t;
 }
 sum = sum / n;
 *s = sqrt(sum);
}

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C Program to implement Radix Sort.

Posted on November 16, 2011 by Sandeepa Nadahalli

Radix sort is an algorithm. Radix Sort sorts the elements by processing its individual digits. Radix sort processing the digits either by Least Significant Digit(LSD) method or by Most Significant Digit(MSD) method. Read more about C Programming Language.

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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
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* and browse!
* 
*                      Happy Coding
***********************************************************/

#include "stdio.h"

#define MAX 100
#define SHOWPASS

void print(int *a, int n) {
 int i;
 for (i = 0; i < n; i++)
  printf("%dt", a[i]);
}

void radix_sort(int *a, int n) {
 int i, b[MAX], m = 0, exp = 1;
 for (i = 0; i < n; i++) {
  if (a[i] > m)
   m = a[i];
 }

 while (m / exp > 0) {
  int box[10] = { 0 };
  for (i = 0; i < n; i++)
   box[a[i] / exp % 10]++;
  for (i = 1; i < 10; i++)
   box[i] += box[i - 1];
  for (i = n - 1; i >= 0; i--)
   b[--box[a[i] / exp % 10]] = a[i];
  for (i = 0; i < n; i++)
   a[i] = b[i];
  exp *= 10;

#ifdef SHOWPASS
  printf("nnPASS   : ");
  print(a, n);
#endif
 }
}

int main() {
 int arr[MAX];
 int i, num;

 printf("nEnter total elements (num < %d) : ", MAX);
 scanf("%d", &num);

 printf("nEnter %d Elements : ", num);
 for (i = 0; i < num; i++)
  scanf("%d", &arr[i]);

 printf("nARRAY  : ");
 print(&arr[0], num);

 radix_sort(&arr[0], num);

 printf("nnSORTED  : ");
 print(&arr[0], num);

 return 0;
}

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K & R C Programs Exercise 1-19

Posted on November 15, 2011 by Sandeepa Nadahalli

K and R C, Solution to Exercise 1-19:
Write a function reverse(str) that reverses the character string str. Use it to write program that reverse thes its input a line at a time. K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language .

/***********************************************************
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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
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* and browse!
* 
*                      Happy Coding
***********************************************************/

#include "stdio.h"

#define MAXINLINE 1000 /* maximum input line size */

int get_lines(char line[], int maxline);
void reverse(char str[]);

/* print longest input line */
main() {

 char line[MAXINLINE]; /* current input line */

 while ((get_lines(line, MAXINLINE)) > 0) {

  reverse(line);
  printf("%s", line);

 }

}

/* getline: read a line into s, return length */
int get_lines(char str[], int line) {
 int c, i, j;

 for (i = 0, j = 0; (c = getchar()) != EOF && c != 'n'; ++i) {
  if (i < line - 1) {
   str[j++] = c;
  }
 }
 if (c == 'n') {
  if (i <= line - 1) {
   str[j++] = c;
  }
  ++i;
 }
 str[j] = '';
 return i;
}

/*reverse the string str*/
void reverse(char str[]) {
 int i, j;
 char temp;
 i = 0;
 while (str[i] != '')
  ++i;
 --i;
 if (str[i] != 'n')

  --i;
 j = 0;
 while (j < i) {
  temp = str[j];
  str[j] = str[i];
  str[i] = temp;
  --i;
  ++j;
 }
}

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K & R C Exercise 1-18

Posted on November 15, 2011 by Sandeepa Nadahalli

K and R C, Solution to Exercise 1-18:
Remove trailing blanks and tabs from each line of input, and to delete entirely blank lines. K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language .

/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include "stdio.h"

#define MAXLINE 1000

int get_lines(char line[], int maxline);
int char remove(char str[]);

main()
{

 char line[MAXINLINE];/* current input line */

 while((get_lines(line,MAXINLINE))>0)
  if(remove(line)> 0)
   printf("%s", line);
 return 0;

}
/*
 remove trailing blanks and tabs from character string str
 */
int remove(char str[])
{
 int i=0;
 while(str[i] !='n')
  ++i;

 --i;

 while(i>=0 && (str[i]==' ' || str[i]=='t'))
  --i;
 if(i>=0)
 {
  ++i;
  s[i]='n';
  ++i;
  s[i]='';

 }
 return i;
}
/* getline: read a line into str, return length */
int get_lines(char str[], int line)
{
 int c, i, j;

 for(i = 0, j = 0; (c = getchar())!=EOF && c != 'n'; ++i)
 {
  if(i < line - 1)
  {
   str[j++] = c;
  }
 }
 if(c == 'n')
 {
  if(i <= line - 1)
  {
   str[j++] = c;
  }
  ++i;
 }
 str[j] = '';
 return i;
}

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K&R C Program Exercise 1-17

Posted on November 15, 2011 by Sandeepa Nadahalli

K and R solution Exercise 1-17,to print all input lines that are longer than 80 characters. K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language .

/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/


#include "stdio.h"
#define MAXINLINE 1000  /* maximum line sizes defined*/
#define LONGLINESIZE  80     /* longer line defined as 80 */
int get_lines(char line[], int maxline);
/*print lines longer than LONGLINESIZE     */
main()
{
 int len;           /*current line length */
 char line[MAXINLINE];/* current input line */
 while((len=get_lines(line,MAXINLINE))>0)
  if(len> LONGLINE)
   printf("%s", line);
 return 0;

}

/* getline: read a line into s, return length */
int get_lines(char s[], int line)
{
 int c, i, j;

 for(i = 0, j = 0; (c = getchar())!=EOF && c != 'n'; ++i)
 {
  if(i < line - 1)
  {
   s[j++] = c;
  }
 }
 if(c == 'n')
 {
  if(i <= line - 1)
  {
   s[j++] = c;
  }
  ++i;
 }
 s[j] = '';
 return i;
}

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K&R C Program Exercise 1-16

Posted on November 15, 2011 by Sandeepa Nadahalli

K and R solutions to Revise the the main routine of the longest-line program so it will correctly print the length of arbitrarily long input lines, and as much as possible of the text. K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language .

/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include "stdio.h"

#define MAXINLINE 1000 /* maximum input line size */

int getline(char line[], int MAXINLINE);
void copy(char to[], char from[]);

/* print longest input line */
int main(void)
{
 int len;               /* current line length */
 int max;               /* maximum length seen so far */
 char line[MAXINLINE];    /* current input line */
 char longest[MAXINLINE]; /* longest line saved here */

 max = 0;

 while((len = getline(line, MAXINLINE)) > 0)
 {
  printf("%d: %s", len, line);

  if(len > max)
  {
   max = len;
   copy(longest, line);
  }
 }
 if(max > 0)
 {
  printf("Longest LINE IN THE PROGRAM is %d characters:n%s", max, longest);
 }
 printf("n");
 return 0;
}

/* getline: read a line into s, return length */
int getline(char s[], int line)
{
 int c, i, j;

 for(i = 0, j = 0; (c = getchar())!=EOF && c != 'n'; ++i)
 {
  if(i < line - 1)
  {
   s[j++] = c;
  }
 }
 if(c == 'n')
 {
  if(i <= line - 1)
  {
   s[j++] = c;
  }
  ++i;
 }
 s[j] = '';
 return i;
}

/* copy: copy 'from' into 'to'; assume 'to' is big enough */
void copy(char to[], char from[])
{
 int k;

 k = 0;
 while((to[k] = from[k]) != '')
 {
  ++k;
 }
}

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K&R C Program Exercise 1-15

Posted on November 15, 2011 by Sandeepa Nadahalli

Rewrite the temperature conversion program (K&R C Program Exercise 1-03 ) to use a function for conversion. K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language .

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* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include "stdio.h"
float celsius(float fahr);
/* Print Fahrenheit-Celsius table
  for fahr=0, 20, . . , 300; float-point version  */
main()
{
 float fahr;
 int lower, upper, step;

 lower = 0;
 upper = 300;
 step = 20;

 fahr = lower;
 while(fahr <= upper)
 {

  printf("%3.0f %6.1fn", fahr, celsius(fahr));
  fahr = fahr + step;
 }

}
/* celsius: convert fahr into celsius */
float celsius(float fahr)
{
 return (5.0 / 9.0) * (fahr - 32.0);
}

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K&R C Program Exercise 1-13

Posted on November 15, 2011 by Sandeepa Nadahalli

K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. K and R solution to print a histogram of the lengths of words in its input. Read more about C Programming Language .

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* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/



#include <stdio.h>

#define MAXLN 10

int main(void)
{
 int c;
 int inspace = 0;
 long lengtharr[MAXLN + 1];
 int wordlen = 0;

 int firstletter = 1;
 long value = 0;
 long maxval = 0;
 int index = 0;
 int done = 0;

 for(index = 0; index <= MAXLN; index++)
 {
  lengtharr[index] = 0;
 }

 while(done == 0)
 {
  c = getchar();

  if(c == ' ' || c == 't' || c == 'n' || c == EOF)
  {
   if(inspace == 0)
   {
    firstletter = 0;
    inspace = 1;

    if(wordlen <= MAXLN)
    {
     if(wordlen > 0)
     {
      value = ++lengtharr[wordlen - 1];
      if(value > maxval)
      {
       maxval = value;
      }
     }
    }
    else
    {
     value = ++lengtharr[MAXLN];
     if(value > maxval)
     {
      maxval = value;
     }
    }
   }
   if(c == EOF)
   {
    done = 1;
   }
  }
  else
  {
   if(inspace == 1 || firstletter == 1)
   {
    wordlen = 0;
    firstletter = 0;
    inspace = 0;
   }
   ++wordlen;
  }
 }

 for(value = maxval; value > 0; value--)
 {
  printf("%4d  | ", value);
  for(index = 0; index <= MAXLN; index++)
  {
   if(lengtharr[index] >= value)
   {
    printf("*  ");
   }
   else
   {
    printf("   ");
   }
  }
  printf("n");
 }
 printf("      +");
 for(index = 0; index <= MAXLN; index++)
 {
  printf("---");
 }
 printf("n       ");
 for(index = 0; index < MAXLN; index++)
 {
  printf("%2d ", index + 1);
 }
 printf(">%dn", MAXLN);

 return 0;
}

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K&R C Program Exercise 1-12

Posted on November 4, 2011 by Sandeepa Nadahalli

K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. C Program that prints its input one word per line.Read more about C Programming Language .

/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/





#include <stdio.h>
int main(void)
{
 int ch;
 int flag;

 flag = 0;
 while((ch = getchar()) != EOF)
 {
  if(ch == ' ' || ch == 't' || ch == 'n')
  {
   if(flag == 0)
   {
    flag = 1;
    putchar('n');
   }

  }
  else
  {
   flag = 0;
   putchar(ch);
  }
 }
 return 0;
}

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K&R C Program Exercise 1-10

Posted on November 4, 2011 by Sandeepa Nadahalli

K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. C Program to Replace each tabs by ‘t’, backspace by ‘b’, and each bakslash by ‘\’.Read more about C Programming Language .

/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include <stdio.h>

#define BACK_SLASH '\'

int main(void)
{
 int c;

 while((c = getchar()) != EOF)
 {
  switch(c)
  {
  case 'b':
   putchar(BACK_SLASH);
   putchar('b');
   break;
  case 't':
   putchar(BACK_SLASH);
   putchar('t');
   break;
  case BACK_SLASH:
   putchar(BACK_SLASH);
   putchar(BACK_SLASH);
   break;
  default:
   putchar(c);
   break;
  }
 }
 return 0;
}

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