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/*************************************************************************/
/*                         Author :  Simon King                          */
/*                         Date   :  April 1995                          */
/*-----------------------------------------------------------------------*/
/*                  EST_DMatrix Class auxilliary functions               */
/*                                                                       */
/*=======================================================================*/
#include <stdlib.h>
#include "EST_DMatrix.h"
#include <limits.h>
#include "EST_math.h"
#include "EST_unix.h"

bool polynomial_fit(EST_DVector &x, EST_DVector &y, 
		    EST_DVector &co_effs, int order)
{
    EST_DVector weights;
    weights.resize(x.n());
    for(int i=0; i<x.n(); ++i)
	weights[i] = 1.0;
    
    return polynomial_fit(x,y,co_effs,weights,order);
}

bool polynomial_fit(EST_DVector &x, EST_DVector &y, EST_DVector &co_effs, 
	       EST_DVector &weights, int order)
{

    if(order <= 0){
	cerr << "polynomial_fit : order must be >= 1" << endl;
	return false;
    }

    if(x.n() != y.n()){
	cerr << "polynomial_fit : x and y must have same dimension" << endl;
	return false;
    }

    if(weights.n() != y.n()){
	cerr << "polynomial_fit : weights must have same dimension as x and y" << endl;
	return false;
    }

    if(x.n() <= order){
	cerr << "polynomial_fit : x and y must have at least order+1 elements"
	    << endl;
	return false;
    }
    

    // matrix of basis function values
    EST_DMatrix A;
    A.resize(x.n(),order+1);
    
    EST_DVector y1;
    y1.resize(y.n());
    
    for(int row=0;row<y.n();row++)
    {
	y1[row] = y[row] * weights[row];
	for(int col=0;col<=order;col++){
	    A(row,col) = pow(x[row],(double)col) * weights[row];
	    
	}
    }
    
    // could call pseudo_inverse, but save a bit by doing
    // it here since we need transpose(A) anyway
    
    EST_DMatrix At, At_A, At_A_inv;
    int singularity=-2;

    transpose(A,At);
    multiply(At,A,At_A);
    
    // error check
    if(!inverse(At_A,At_A_inv,singularity))
    {
	cerr << "polynomial_fit : inverse failed (";
	if(singularity == -2)
	    cerr << "unspecified reason)" << endl;
	else if(singularity == -1)
	    cerr << "non-square !!)" << endl;
	else
	{
	    cerr << "singularity at point : " << singularity;
	    cerr << " = " << x[singularity] << "," << y[singularity];
	    cerr << " )" << endl;
	}
	return false;
    }
    
    EST_DVector At_y1 = At * y1;
    co_effs = At_A_inv * At_y1;
    return true;
    
}

double matrix_max(const EST_DMatrix &a)
{
    int i, j;
    double v = INT_MIN;
    
    for (i = 0; i < a.num_rows(); ++i)
	for (j = 0; j < a.num_columns(); ++j)
	    if (a.a_no_check(i, j) > v)
		v = a.a_no_check(i, j);
    
    return v;
}

int square(const EST_DMatrix &a)
{
    return a.num_rows() == a.num_columns();
}
// add all elements in matrix.
double sum(const EST_DMatrix &a)
{
    int i, j;
    double t = 0.0;
    for (i = 0; i < a.num_rows(); ++i)
	for (j = 0; j < a.num_columns(); ++j)
	    t += a.a_no_check(i, j);
    return t;
}

// set all elements not on the diagonal to zero.
EST_DMatrix diagonalise(const EST_DMatrix &a)
{
    int i;
    EST_DMatrix b(a, 0);	// initialise and fill b with zeros

    if (a.num_rows() != a.num_columns())
    {
	cerr << "diagonalise: non-square matrix ";
	return b;
    }
    
    for (i = 0; i < a.num_rows(); ++i)
	b(i, i) = a.a_no_check(i, i);
    
    return b;
}

// set all elements not on the diagonal to zero.
void inplace_diagonalise(EST_DMatrix &a)
{
    // NB - will work on non-square matrices without warning
    int i,j;
    
    for (i = 0; i < a.num_rows(); ++i)
	for (j = 0; j < a.num_columns(); ++j)
	    if(i != j)
		a.a_no_check(i, j) = 0;
}

EST_DMatrix sub(const EST_DMatrix &a, int row, int col)
{
    int i, j, I, J;
    int n = a.num_rows() - 1;
    EST_DMatrix s(n, n);
    
    for (i = I = 0; i < n; ++i, ++I)
    {
	if (I == row)
	    ++I;
	for (j = J = 0; j < n; ++j, ++J)
	{
	    if (J == col)
		++J;
	    s(i, j) = a.a(I, J);
	}
    }
    
    //    cout << "sub: row " << row  << " col " << col << "\n" << s;
    
    return s;
}

EST_DMatrix row(const EST_DMatrix &a, int row)
{
    EST_DMatrix s(1, a.num_columns());
    int i;
    
    for (i = 0; i < a.num_columns(); ++i)
	s(0, i) = a.a(row, i);
    
    return s;
}

EST_DMatrix column(const EST_DMatrix &a, int col)
{
    EST_DMatrix s(a.num_rows(), 1);
    int i;
    
    for (i = 0; i < a.num_rows(); ++i)
	s(i, 0) = a.a(i, col);
    
    return s;
}

EST_DMatrix triangulate(const EST_DMatrix &a)
{
    EST_DMatrix b(a, 0);
    int i, j;
    
    for (i = 0; i < a.num_rows(); ++i)
	for (j = i; j < a.num_rows(); ++j)
	    b(j, i) = a.a(j, i);
    
    return b;
}

void transpose(const EST_DMatrix &a,EST_DMatrix &b)
{
    int i, j;
    b.resize(a.num_columns(), a.num_rows());
    
    for (i = 0; i < b.num_rows(); ++i)
	for (j = 0; j < b.num_columns(); ++j)
	    b.a_no_check(i, j) = a.a_no_check(j, i);
}

EST_DMatrix backwards(EST_DMatrix &a)
{
    int i, j, n;
    n = a.num_columns();
    EST_DMatrix t(n, n);
    
    for (i = 0; i < n; ++i)
	for (j = 0; j < n; ++j)
	    t(n - i - 1, n - j - 1) = a.a(i, j);
    
    return t;
}


// changed name from abs as it causes on at least on POSIX machine
// where int abs(int) is a macro
EST_DMatrix DMatrix_abs(const EST_DMatrix &a)
{
    int i, j;
    EST_DMatrix b(a, 0);
    
    for (i = 0; i < a.num_rows(); ++i)
	for (j = 0; j < a.num_columns(); ++j)
	    b.a_no_check(i, j) = fabs(a.a_no_check(i, j));
    
    return b;
}

static void row_swap(int from, int to, EST_DMatrix &a)
{
    int i;
    double f;

    if (from == to)
	return;

    for (i=0; i < a.num_columns(); i++)
    {
	f = a.a_no_check(to,i);
	a.a_no_check(to,i) = a.a_no_check(from,i);
	a.a_no_check(from,i) = f;
    }
}

int inverse(const EST_DMatrix &a,EST_DMatrix &inv)
{
    int singularity=0;
    return inverse(a,inv,singularity);
}

int inverse(const EST_DMatrix &a,EST_DMatrix &inv,int &singularity)
{

    // Used to use a function written by Richard Tobin (in C) but 
    // we no longer need C functionality any more.   This algorithm 
    // follows that in "Introduction to Algorithms", Cormen, Leiserson
    // and Rivest (p759) and the term Gauss-Jordon is used for some part,
    // As well as looking back at Richard's.
    // This also keeps a record of which rows are which from the original
    // so that it can return which column actually has the singularity
    // in it if it fails to find an inverse.
    int i, j, k;
    int n = a.num_rows();
    EST_DMatrix b = a;  // going to destructively maniplate b to get inv
    EST_DMatrix pos;    // the original position
    double biggest,s;
    int r=0,this_row,all_zeros;

    singularity = -1;
    if (a.num_rows() != a.num_columns())
	return FALSE;

    // Make the inverse the identity matrix.
    inv.resize(n,n);
    pos.resize(n,1);
    for (i=0; i<n; i++)
	for (j=0; j<n; j++)
	    inv.a_no_check(i,j) = 0.0;
    for (i=0; i<n; i++)
    {
	inv.a_no_check(i,i) = 1.0;
	pos.a_no_check(i,0) = (double)i;
    }

    // Manipulate b to make it into the identity matrix, while performing
    // the same manipulation on inv.  Once b becomes the identity inv will
    // be the inverse (unless theres a singularity)

    for (i=0; i<n; i++)
    {
	// Find the absolute largest val in this col as the next to
	// manipuate
	biggest = 0.0;
	r = 0;
	for (j=i; j<n; j++)
	{
	    if (fabs(b.a_no_check(j,i)) > biggest)
	    {
		r = j;
		biggest = fabs(b.a_no_check(j,i));
	    }
	}

	if (biggest == 0.0)  // oops found a singularity
	{   
	    singularity = (int)pos.a_no_check(i,0);
	    return FALSE;
	}

	// Swap current with biggest
	this_row = (int)pos.a_no_check(i,0);  // in case we need this number
	row_swap(r,i,b);
	row_swap(r,i,inv);
	row_swap(r,i,pos);

	// Make b(i,i) = 1
	s = b(i,i);
	for (k=0; k<n; k++)
	{
	    b.a_no_check(i,k) /= s;
	    inv.a_no_check(i,k) /= s;
	}

	// make rest in col(i) 0
	for (j=0; j<n; j++)
	{
	    if (j==i) continue;
	    s = b.a_no_check(j,i);
	    all_zeros = TRUE;
	    for (k=0; k<n; k++)
	    {
		b.a_no_check(j,k) -= b.a_no_check(i,k) * s;
		if (b.a_no_check(j,k) != 0)
		    all_zeros = FALSE;
		inv.a_no_check(j,k) -= inv.a_no_check(i,k) * s;
	    }
	    if (all_zeros)
	    {
		// printf("singularity between (internal) columns %d %d\n",
		//       this_row,j);
		// always identify greater row so linear regression
		// can preserve intercept in column 0
		singularity = ((this_row > j) ? this_row : j);
		return FALSE;
	    }
	}
    }

    return TRUE;
}

int pseudo_inverse(const EST_DMatrix &a, EST_DMatrix &inv)
{
    int singularity=0;
    return pseudo_inverse(a,inv,singularity);
}

int pseudo_inverse(const EST_DMatrix &a, EST_DMatrix &inv,int &singularity)
{
    // for non-square matrices
    // useful for solving linear eqns
    // (e.g. polynomial fitting)
    
    // is it square ?
    if( a.num_rows() == a.num_columns() )
	return inverse(a,inv,singularity);
    
    if( a.num_rows() < a.num_columns() )
	return FALSE;
    
    EST_DMatrix a_trans,atrans_a,atrans_a_inverse;

    transpose(a,a_trans);
    multiply(a_trans,a,atrans_a);
    if (!inverse(atrans_a,atrans_a_inverse,singularity))
	return FALSE;
    multiply(atrans_a_inverse,a_trans,inv);
    
    return TRUE;
}


double determinant(const EST_DMatrix &a)
{
    int i, j;
    int n = a.num_rows();
    double det;
    if (!square(a))
    {
	cerr << "Tried to take determinant of non-square matrix\n";
	return 0.0;
    }
    
    EST_DVector A(n);
    
    if (n == 2)			// special case of 2x2 determinant
	return (a.a_no_check(0,0) * a.a_no_check(1,1)) - 
	    (a.a_no_check(0,1) * a.a_no_check(1,0));
    
    double p;
    
    // create cofactor matrix
    j = 1;
    for (i = 0; i < n; ++i)
    {
	p = (double)(i + j + 2);	// because i & j should start at 1
	//	cout << "power " <<p << endl;
	A[i] = pow(-1.0, p) * determinant(sub(a, i, j));
    }
    //    cout << "cofactor " << A;
    
    // sum confactor and original matrix 
    det = 0.0;
    for (i = 0; i < n; ++i)
	det += a.a_no_check(i, j) * A[i];
    
    return det;
}

void eye(EST_DMatrix &a, const int n)
{
    int i,j;
    a.resize(n,n);
    for (i=0; i<n; i++)
    {
	for (j=0; j<n; j++)
	    a.a_no_check(i,j) = 0.0;
	
	a.a_no_check(i,i) = 1.0;
    }
}

void eye(EST_DMatrix &a)
{
    int i,n;
    n=a.num_rows();
    if(n != a.num_columns())
    {
	cerr << "Can't make non-square identity matrix !" << endl;
	return;
    }

    a.fill(0.0);
    for (i=0; i<n; i++)
	a.a_no_check(i,i) = 1.0;
}

EST_DVector add(const EST_DVector &a,const EST_DVector &b)
{
    // a - b
    EST_DVector *ans = new EST_DVector;
    int i;

    if(a.length() != b.length())
    {
	cerr << "Can't subtract vectors of differing lengths !" << endl;
	ans->resize(0);
	return *ans;
    };

    ans->resize(a.length());

    for(i=0;i<a.length();i++)
	ans->a_no_check(i) = a.a_no_check(i) + b.a_no_check(i);

    return *ans;
}

EST_DVector subtract(const EST_DVector &a,const EST_DVector &b)
{
    // a - b
    EST_DVector *ans = new EST_DVector;
    int i;

    if(a.length() != b.length())
    {
	cerr << "Can't subtract vectors of differing lengths !" << endl;
	ans->resize(0);
	return *ans;
    };

    ans->resize(a.length());

    for(i=0;i<a.length();i++)
	ans->a_no_check(i) = a.a_no_check(i) - b.a_no_check(i);

    return *ans;
}

EST_DVector diagonal(const EST_DMatrix &a)
{

    EST_DVector ans;
    if(a.num_rows() != a.num_columns())
    {
	cerr << "Can't extract diagonal of non-square matrix !" << endl;
	return ans;
    }
    int i;
    ans.resize(a.num_rows());
    for(i=0;i<a.num_rows();i++)
	ans.a_no_check(i) = a.a_no_check(i,i);

    return ans;
}

double polynomial_value(const EST_DVector &coeffs, const double x)
{
    double y=0;

    for(int i=0;i<coeffs.length();i++)
	y += coeffs.a_no_check(i) * pow(x,(double)i);

    return y;
}

void symmetrize(EST_DMatrix &a)
{
    // uses include enforcing symmetry
    // of covariance matrices (to compensate
    // for rounding errors)

    double f;

    if(a.num_columns() != a.num_rows())
    {
	cerr << "Can't symmetrize non-square matrix !" << endl;
	return;
    }
	      
    // no need to look at entries on the diagonal !
    for(int i=0;i<a.num_rows();i++)
	for(int j=i+1;j<a.num_columns();j++)
	{
	    f = 0.5 * (a.a_no_check(i,j) + a.a_no_check(j,i));
	    a.a_no_check(i,j) = a.a_no_check(j,i) = f;
	    }
}

void 
stack_matrix(const EST_DMatrix &M, EST_DVector &v)
{
    v.resize(M.num_rows() * M.num_columns());
    int i,j,k=0;
    for(i=0;i<M.num_rows();i++)
	for(j=0;j<M.num_columns();j++)
	    v.a_no_check(k++) = M(i,j);
}


void
make_random_matrix(EST_DMatrix &M, const double scale)
{

    double r;
    for(int row=0;row<M.num_rows();row++)
	for(int col=0;col<M.num_columns();col++)
	{
	    r = scale * ((double)rand()/(double)RAND_MAX);
	    M.a_no_check(row,col) = r;
	}
}

void
make_random_vector(EST_DVector &V, const double scale)
{

    double r;
    for(int i=0;i<V.length();i++)
    {
	r = scale * ((double)rand()/(double)RAND_MAX);
	V.a_no_check(i) = r;
    }
}

void
make_random_symmetric_matrix(EST_DMatrix &M, const double scale)
{
    if(M.num_rows() != M.num_columns())
    {
	cerr << "Can't make non-square symmetric matrix !" << endl;
	return;
    }

    double r;

    for(int row=0;row<M.num_rows();row++)
	for(int col=0;col<=row;col++)
	{
	    r = scale * ((double)rand()/(double)RAND_MAX);
	    M.a_no_check(row,col) = r;
	    M.a_no_check(col,row) = r;
	}
}

void 
make_random_diagonal_matrix(EST_DMatrix &M, const double scale)
{
    if(M.num_rows() != M.num_columns())
    {
	cerr << "Can't make non-square symmetric matrix !" << endl;
	return;
    }

    M.fill(0.0);
    for(int row=0;row<M.num_rows();row++)
	M.a_no_check(row,row) = scale * ((double)rand()/(double)RAND_MAX);


}

void
make_poly_basis_function(EST_DMatrix &T, EST_DVector t)
{
    if(t.length() != T.num_rows())
    {
	cerr << "Can't make polynomial basis function : dimension mismatch !" << endl;
	cerr << "t.length()=" << t.length();
	cerr << "   T.num_rows()=" << T.num_rows() << endl;
	return;
    }
    for(int row=0;row<T.num_rows();row++)
	for(int col=0;col<T.num_columns();col++)
	    T.a_no_check(row,col) = pow(t[row],(double)col);
    
}

int
floor_matrix(EST_DMatrix &M, const double floor)
{
    int i,j,k=0;
    for(i=0;i<M.num_rows();i++)
	for(j=0;j<M.num_columns();j++)
	    if(M.a_no_check(i,j) < floor)
	    {
		M.a_no_check(i,j) = floor;
		k++;
	    }
    return k;
}

EST_DMatrix
cov_prod(const EST_DVector &v1,const EST_DVector &v2)
{
    // form matrix of vector product, e.g. for covariance
    // treat first arg as a column vector and second as a row vector

    EST_DMatrix m;
    m.resize(v1.length(),v2.length());
    
    for(int i=0;i<v1.length();i++)
	for(int j=0;j<v2.length();j++)
	    m.a_no_check(i,j) = v1.a_no_check(i) * v2.a_no_check(j);

    return m;
}
