/* 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;
}

# Solving a quadratic equation.

import math
import sys

a = float(input('Enter a='))
b = float(input('Enter b='))
c = float(input('Enter c='))

disc = b*b - 4*a*c

if disc < 0:
    print('Imaginary !\n')
    sys.exit(0)

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

print("The roots are %f and %f.\n"%(x1,x2))

 

#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;
}

# Sums up a series

import math
sum = 0
for i in range(1001):
      sum = sum+(-1)**i/float(2*i + 1)

print("The summation and the exact values are %f and %f.\n"%(sum, math.atan(1.0)))


 

#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;
}

import math
import sys

N=10

x=[-4.0, 1.2, 1.3, 2.5, -12.7,  9.0, 1.41, 65.2, -2.1, 2.36]

sum = 0
variance = 0

for i in range(N):
   sum = sum + x[i]

average=sum/N

for i in range(N):
    variance+= (x[i] - average)**2

variance = variance/(N - 1)

print("avg=%f, stddev=%f"%(average, math.sqrt(variance)))


 

#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;
}

import sys

def f(x):
 return x*x - 2

def fp(x):
 return 2*x

def newton(x):
   return x - f(x)/fp(x)

x1=float(input('Enter initial guess = '))

if fp(x1) == 0:
    print('No convergence !\n')
    sys.exit(0)

for i in range(100):
   x2 = newton(x1)
   if abs(x1-x2)<0.0000001:
       break
   x1=x2

print("Iteration=%d.\n"%(i))
print("x=%f"%(x1))

 

#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;
}

fp1 = open('junk1.dat', 'r')
a = fp1.readline()
fp1.close()

fp2 = open('junk2.dat', 'w')
fp2.write(a)
fp2.close()