solution to a linear system of equations

This is a discussion on solution to a linear system of equations within the C++ Programming forums, part of the General Programming Boards category; http://www.scs.carleton.ca/~wli/2404...Assign1W09.doc In the first part the procedure that I followed is as follows. Is it in accordance with the requirements. ...

  1. #1
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    solution to a linear system of equations

    http://www.scs.carleton.ca/~wli/2404...Assign1W09.doc

    In the first part the procedure that I followed is as follows. Is it in accordance with the requirements.

    Code:
    class Main
    {
    public:
    Main(void);
    ~Main(void);
    void main(){
    double a[100][100], b[100][100], d[100][100], c[100], e[100], maxele, temp;
    
    cout<<" Please enter the number of unknowns: ";
    for(int i=0; i<n; i++){
    for(int j=0; j<n; j++)
    cin>>a[i][j];
    }
    for(int i=0; i<n; i++){
    cin>>c[i];
    }
    for(int i=0; i<n; i++){
    for(int j=0; j<n; j++){
    if(a[i][j]<0){
    b[i][j]=-1*a[i][j];
    }
    else{
    b[i][j]=a[i][j];
    }
    } 
    }
    
    int k=0;
    for(int i=0; i<n; i++){
    k<--i;
    while(j<n){
    if(a[i][j]>a[i][k]){
    temp<--a[i][k];
    a[i][k]<--a[i][j];
    a[i][j]<--temp;
    maxele<--a[i][k];
    j++;
    k++;
    }
    } 
    } 
    
    
    for(int i=0; i<n; i++){
    for(int j=0; j<n; j++){
    d[i][j]<--a[i][j]/a[i][1];
    }
    }
    
    for(int i=0; i<n; i++){
    if(a[i][1]<a[++i][1]){
    for(int j=0; j<n; j++){
    a[i][j]<--a[++i][j];
    }
    }
    }
    
    for(int i=0; i<n; i++){
    if(a[i][i]<1 && a[i][i]>1E-9){
    cout<<"the system does not have a unique solution";
    break;
    }
    else{
    for(int j=0; j<n; j++){
    a[i][j]<--a[i][j]-d[i][j];
    } 
    }
    }
    break;
    }
    
    static const int i=50;
    static const int j=50;
    
    while(i>0) do{
    while(j>0) do{
    if(a[i][j]<1 && a[i][j]>1E-9){
    break;
    }
    else{
    e[i]=(b[i]-a[i][--j])/a[i][j]; 
    }
    }
    }
    
    /*for(int i=sizeof a; i>0; i--){
    for(int j=sizeof a; j>0; j--){
    if(a[i][j]<1 && a[i][j]>1E-9){
    break;
    }
    else{
    e[i]=(b[i]-a[i][--j])/a[i][j]; 
    }
    }
    }*/
    }
    
    private:
    
    };

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    I didn't read the requirements, but I doubt that your requirements are to write ... whatever that is. If it's supposed to be C++, it needs a heck of a lot of work. Your main program is never inside of a class. There's no reason to have a class if you don't need one, and you don't seem to need one. Are you using "<--" for assignment? In C++, that's "=". I'm sure there's more.

  3. #3
    Cat without Hat CornedBee's Avatar
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    Like, what the hell happened to the poor whitespace? Don't you have any pity on that poor whitespace?
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  4. #4
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    i believe you've done the partial pivoting wrong.

  5. #5
    Kiss the monkey. CodeMonkey's Avatar
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    This chunk of code is mysterious
    Code:
    double a[100][100], b[100][100], d[100][100], c[100], e[100], maxele, temp;
    
    cout<<" Please enter the number of unknowns: ";
    for(int i=0; i<n; i++){
    for(int j=0; j<n; j++)
    cin>>a[i][j];
    }
    n is not defined. Did you want to ask the user for n, and then ask him/her to enter n squared values? It seems n should be fixed at 100.
    Also, please indent your code: the logic is simple enough to follow, but the branches would be clearer with indentation.
    Last edited by CodeMonkey; 01-15-2009 at 08:01 PM. Reason: italics
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

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