/* This program computes roots 
for quadratic equation. */
#include <stdio.h>
#include <math.h>

int main()
{
double a, b, c, disc, x1, x2;

printf("Enter 3 coeffs separated by space =");
scanf("%lf %lf %lf", &a, &b, &c);

disc=b*b-4*a*c;

if (disc<= 0) 
  { printf("Imaginary roots !\n"); return 0;}

x1= (-b + sqrt(disc))/(2*a);
x2= (-b - sqrt(disc))/(2*a);

printf("The roots are %lf and %lf. \n", x1, x2);

return 0;
}

C     This program computes roots 
C       for quadratic equations.
      DOUBLE PRECISION A, B, C, DISC, X1,X2
      WRITE(*,*) "Enter three coefficients"
      READ(*,*) A, B, C
      DISC=B**2-4.0*A*C

      IF(DISC.LE.0.0) THEN
       WRITE(*,*) "Imaginary roots !"
      STOP
      ENDIF

      X1=(-B+SQRT(DISC))/(2.0*A)
      X2=(-B-SQRT(DISC))/(2.0*A)
      WRITE(*,*) "Roots are ", X1, X2
      STOP
      END

 

#include <stdio.h>
#include <math.h>

int main()
{
  int i;
  double sum = 0.0;
  for (i=0; i<1000; i++) 
    sum+=pow(-1,i)/(double)(2*i+1);
  printf("approx= %f true value= %lf\n ",
   4*sum, 4*atan(1.0));
return 0;
}

      DOUBLE PRECISION SUM
      INTEGER I
      SUM=0.0

      DO 10 I=0,999,1
       SUM=SUM+(-1)**I/(2.0*FLOAT(I)+1.0)
 10   CONTINUE

      WRITE(*,*) "Approx and exact values =", 4.0*SUM,
     c  4.0*ATAN(1.0)
      STOP
      END

 

#include <stdio.h>
#include <math.h>

#define N 10

int main()
{
  float x[]={ -4.0, 1.2, 1.3, 2.5, -12.7, 
   9.0, 1.41, 65.2, -2.1, 2.36};
  int i;
  float sum = 0.0, average, variance;

  for (i=0; i<N; i++) sum+=x[i];
  average=sum/N;

  for (i=0; i<N; i++) 
   variance += pow(x[i]-average, 2);
  variance = variance/(N-1);

  printf("avg.= %f std. dev. = %f \n ",
    average, sqrt(variance));
  return 0;
}

      PARAMETER(N=10)
      REAL X(N), SUM, AVE, VAR
      INTEGER I

      DATA X /-4.0,1.2,1.3,2.5,-12.7,9.0,1.41,
     c 65.2,-2.1, 2.36/

      SUM=0.0

      DO 10 I=1,N
       SUM=SUM+X(I)
 10   CONTINUE

      AVE=SUM/FLOAT(N)

      DO 20 I=1,N
       VAR=VAR+(X(I)-AVE)**2
 20   CONTINUE
      VAR=VAR/(FLOAT(N)-1.0)

      WRITE(*,*) "Average=", AVE,
     c  ' Standard deviation =', SQRT(VAR)
      STOP
      END

 

#include <stdio.h>
#include <math.h>
#define EPS 1.0e-6

double f(double x)
{
	return x*x-2;
}

double fp(double x)
{
	return 2*x;
}

double newton(double x)
{
	return x - f(x)/fp(x);
}

int main()
{
	double x1, x2;
	int i;

	printf("Enter initial guess  =");
	scanf("%lf", &x1);

	if (fp(x1)==0.0) {
		printf("No convergence.\n");
		return;
	}

	for (i=0;i<100;i++)
	{
		x2=newton(x1);
		if (fabs(x1-x2)< EPS) break;
		x1=x2;
	}

	printf("iteration = %d\n", i);
	printf("x= %lf\n", x1);
	return 0;
}

******************************
      FUNCTION F(X)
      DOUBLE PRECISION F, X
      F=X*X-2.0
      RETURN
      END
******************************
      FUNCTION FP(X)
      DOUBLE PRECISION FP, X
      FP=2.0*X
      RETURN
      END
******************************
      FUNCTION NEWTON(X)
      DOUBLE PRECISION NEWTON, X, F, FP
      NEWTON=X-F(X)/FP(X)
      RETURN
      END
****************************

      PARAMETER(EPS=1.0E-6)
      DOUBLE PRECISION X1, X2, NEWTON, F, FP
      INTEGER I

      WRITE(*,*) "Enter initial guess"
      READ(*,*) X1

      IF(FP(X1).EQ.0.0) THEN
        WRITE(*,*) "No convergence"
        STOP
      ENDIF

      DO 10 I=0,99,1
       X2=NEWTON(X1)
       IF(ABS(X1-X2).LT.EPS) GOTO 11
       X1=X2
 10   CONTINUE

 11   CONTINUE

      WRITE(*,*)"Iteration =",I
      WRITE(*,*)"X=",X1

      STOP
      END

 

#include <stdio.h>
int main()
{
   FILE *fp1, *fp2; 
   float a,b,c;
   fp1=fopen("junk1.dat","r");
   fscanf(fp1, "%f", &a);
   fclose(fp1)

   fp2=fopen("junk2.dat","w");
   fprintf(fp2,"This is the first file.\n");
   fclose(fp2);

   return 0;
}

      REAL A, B, C
      B=3.14
C
      OPEN(UNIT=1, FILE='junk1.dat', STATUS='old')
      READ(1, *) A
      WRITE(*,*) A
      CLOSE (1)
C
      OPEN(UNIT=2, FILE='junk2.dat', STATUS='new')
      WRITE(2,*) 'This is the first file.'
      WRITE(2,*) B
      CLOSE(2)
C
      STOP
      END