# An example of C++ implementation for solving a multivariate first order equation

• 2020-06-03 07:29:37
• OfStack

An example of C++ is presented in this paper. To share for your reference, specific as follows:

Note: The isometric matrix of n*n is calculated here. The code is as follows:

``````
#include<iostream>
#include<math.h>
#include<fstream>
#include<stdlib.h>
using namespace std;
void print(double (*pArray), int iWidth,int iHigh);
void main(){
int n,m;
double a = {
{100, 10, 1, 10},
{400, 20, 1, 20},
{900, 30, 1, 10},
};// The first 4 The columns are augmented matrices
int i,j;
n = 3;
cout<<" The interface number of the input system: ";
cout<<n<<endl;
cout<<" Input augmented matrix: "<<endl;
for(i = 0; i < n; i++){
for(j = 0; j < n + 1;j++){
cout<<a[i][j]<<"  ";
}
cout<<endl;
}
for(j = 0; j < n; j++){
double max = 0;
double imax = 0;
for(i = j; i < n; i++){
if(imax < fabs(a[i][j])){
imax = fabs(a[i][j]);
max = a[i][j];// Gets the largest element in the column of each row
m = i;
}
}
if(fabs(a[j][j]) != max) {
double b = 0;
for(int k = j;k < n + 1; k++){
b = a[j][k];
a[j][k] = a[m][k];
a[m][k] = b;
}
}
print(a, 3, 4);
for(int r = j;r < n + 1;r++){
a[j][r] = a[j][r] / max;// Divide the row's column by its first column 1 The goal is to make the first element zero 1
}
print(a, 3, 4);
for(i = j + 1;i < n; i++){
double c = a[i][j];
if(c == 0) continue;
for(int s = j;s < n + 1;s++){
double tempdata = a[i][s];
a[i][s] = a[i][s] - a[j][s] * c;// Subtract the number of rows before and after, bring down 1 On line or 1 The first element of the row is 0
print(a, 3, 4);
}
print(a, 3, 4);
}
print(a, 3, 4);
}
for(i = n - 2; i >= 0; i--){
for(j = i + 1;j < n; j++){
double tempData = a[i][j];
double data1 = a[i][n];
double data2 = a[j][n];
a[i][n] = a[i][n] - a[j][n] * a[i][j];
print(a, 3, 4);
}
}
print(a, 3, 4);
cout<<" The solution to the system is: "<<endl;
for(int k = 0; k < n; k++){
cout<<"x"<<k<<" = "<<a[k][n]<<endl;
}
}
void print(double (*pArray), int iWidth,int iHigh) {
std::cout<<"Array: "<<"\n";
for(int i = 0; i < iWidth; i++){
for(int j = 0; j < iHigh;j++){
cout<<pArray[i][j]<<"  ";
}
cout<<endl;
}
}

``````

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