哪位知道下面这个函数的功能啊！谢谢

int HOUS(double c[][MMax], double d[], double x[], double eps, double &rd, int m, int n)
{
/*
c: c[1..n][1..m]
d: d[1..n]
m: the number of unknown
n: the number of equations
rd: ||d+cx||
*/
double lk, ckk, beta, sm;
double qk[MMax], ad[MMax];
int i,j,k;

for(k=1; k<=m; k++){

for(sm=0, i=k; i<=n; i++)
  sm+=c[i][k]*c[i][k];       //ak^2=sigma(cik*cik) for i=k to n

if(sm < eps)
  return -1;                //error occurs

ckk=c[k][k];
lk=ckk<0? sqrt(sm) : -sqrt(sm);     //lk = -sign(ckk)*sqrt(sm)
                                    //L={0, ..., lk, 0, ..., 0}
                                    //S={0,..., ckk, ck+1,k, ..., cn,k}
ad[k]=lk;
                //sigma=||S-L||^2=(ckk-lk)^2 + S*S - ckk^2
                            // =S*S + (2ckk-lk)(-lk)
                            // =lk^2 - 2ckk*lk +lk^2
                            // =2lk^2-2ckk*lk
                            // =2sm-2ckk*lk
beta=1/(sm-ckk*lk);        //2 / sigma =1/(sm-ckk*lk)
c[k][k]=ckk-lk;            //U=S-L

if(k<m)
  for(j=k+1; j<=m; j++){
    for(sm=0, i=k; i<=n; i++)
      sm+=c[i][k]*c[i][j];  //U*cj
    qk[j]=beta*sm;          //Qkj=2U*cj/sigma
    for(i=k; i<=n; i++)
      c[i][j]-=c[i][k]*qk[j];
  }

for(sm=0, i=k; i<=n; i++)
  sm+=c[i][k]*d[i];
sm*=beta;

for(i=k; i<=n; i++)
  d[i]-=c[i][k]*sm;

}// tri-anglized

for(i=m; i>=1; i--){
d[i]/=ad[i];
x[i]=d[i];
if(i>1)
for(j=1; j<i; j++)
d[j]-=c[j][i]*d[i];
}

for(rd=0, i=m+1; i<=n; i++)
rd+=d[i]*d[i]; // remained error
return 0;
}