Benito
27 de Abril del 2005

hola muchachos! necesito saber si alguien tiene un programa para resolver sistemas de ecuaciones lineales por método de nuestro estimado Gauss. En caso de tenerlo, agradecería q me lo envíen a [email protected]
gracias!

Noel Solw
27 de Abril del 2005

// program k5a10.CPP - page 83
// for a given matrix float [N][N+1] find the soluction vector
// float x[N] by Gaussian elimination method.
// 7/8/2001
// written in Borland CPP ver 3.1

#include <conio.h>
#include <iostream.h>
#include <iomanip.h>
#include <stdlib.h>
#include <math.h>

#define N 5

void Init(float a[N][N+1],float x[N])
{
randomize();
int i,j;
for(i = 0; i < N; i++)
{
for(j = 0; j < N+1; j++)
a[i][j] = random(21)-10;
x[i] = 0;
}
} // INIT

void ShowSystem(float a[N][N+1],char *msg)
{
for(int i = 0; i < N; i++)
{
cout << setw(15) << msg;
msg[0] = 0;
for(int j = 0; j < N+1; j++)
cout << setw(10) << a[i][j];
cout << endl;
}
cout << endl;
} // SHOW SYSTEM

void Swap(float &a,float &b)
{
float c = a;
a = b;
b = c;
} // SWAP FLOAT

void Pivotting(float a[N][N+1],int k)
{
int index = k;
for(int i = k+1; i < N; i++)
if(fabs(a[i][k]) > fabs(a[index][k]))
index = i;
if(index != k)
for(int j = 0; j < N+1; j++)
Swap(a[index][j],a[k][j]);
} // PIVOTTING

void ErrorExit(float a[N][N+1])
{
ShowSystem(a,"system :");
cout << "singular system - program halts ! ! !" << endl << endl;
exit(0);
} // ERROR EXIT

void Process(float a[N][N+1],float x[N])
{
for(int i = 0; i < N-1; i++)
{
Pivotting(a,i);
if(!a[i][i])
ErrorExit(a);
for(int k = i+1; k < N; k++)
for(int j = i; j < N+1; j++)
a[k][j] -= a[i][j]*a[k][j]/a[i][i];
}
ShowSystem(a,"system :");
for(;i >= 0;i--)
{
x[i] = a[i][N];
for(int j = N-1; j > i;j--)
x[i] -= a[i][j]*x[j];
if(!a[i][i])
ErrorExit(a);
x[i] /= a[i][i];
}
} // PROCESS

void Verification(float a[N][N+1],float x[N])
{
cout << "verification : " << endl << endl;
for(int i = 0; i < N; i++)
{
float sum = 0;
for(int j = 0; j < N; j++)
sum += a[i][j]*x[j];
cout << "x[" << i << "] = " << setw(8) << x[i] << setw(20)
<< sum << setw(9) << " = " << setw(11) << a[i][N] << endl;
}
cout << endl;
} // VERIFICATION

void main()
{
clrscr();
float a[N][N+1],x[N];
Init(a,x);
cout << setprecision(3) << setiosflags(ios::showpoint)
<< setiosflags(ios::fixed);
ShowSystem(a,"system :");
Process(a,x);
Verification(a,x);
cout << "end of program - good bye ! ! !n";
getch();
} // MAIN