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Mat2.cc

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/*
    File:           Mat2.cc

    Function:       Implements Mat2.h

    Author(s):      Andrew Willmott

    Copyright:      (c) 1995-2000, Andrew Willmott

    Notes:          

*/

#include "vl/Mat2.h"
#include <ctype.h>
#include <iomanip.h>


Bool TMat2::operator == (const TMat2 &m) const
{
    return(row[0] == m[0] && row[1] == m[1]);
}

Bool TMat2::operator != (const TMat2 &m) const
{
    return(row[0] != m[0] || row[1] != m[1]);
}


TMReal det(const TMat2 &m)
{
    return(dot(m[0], cross(m[1])));
}

TMat2 inv(const TMat2 &m)
{
    TMReal          mDet;
    TMat2           result;
    
    result[0][0] =  m[1][1]; result[0][1] = -m[0][1]; 
    result[1][0] = -m[1][0]; result[1][1] =  m[0][0]; 
    
    mDet = m[0][0] * result[0][0] + m[0][1] * result[1][0];
    Assert(mDet != 0.0, "(Mat2::inv) matrix is non-singular");
    result /= mDet;
    
    return(result);
}

TMat2 oprod(const TMVec2 &a, const TMVec2 &b)
// returns outerproduct of a and b:  a * trans(b)
{
    TMat2   result;

    result[0] = a[0] * b;
    result[1] = a[1] * b;

    return(result);
}

ostream &operator << (ostream &s, const TMat2 &m)
{
    Int w = s.width();

    return(s << '[' << m[0] << endl << setw(w) << m[1] << ']' << endl);
}

istream &operator >> (istream &s, TMat2 &m)
{
    TMat2   result;
    Char    c;
    
    // Expected format: [[1 2] [3 4]]
    // Each vector is a row of the row matrix.
    
    while (s >> c && isspace(c))        // ignore leading white space
        ;
        
    if (c == '[')           
    {
        s >> result[0] >> result[1];

        if (!s)
        {
            cerr << "Expected number while reading matrix\n";
            return(s);
        }
            
        while (s >> c && isspace(c))
            ;
            
        if (c != ']')
        {
            s.clear(ios::failbit);
            cerr << "Expected ']' while reading matrix\n";
            return(s);
        }
    }
    else
    {
        s.clear(ios::failbit);
        cerr << "Expected '[' while reading matrix\n";
        return(s);
    }
    
    m = result;
    return(s);
}


TMat2 &TMat2::MakeRot(Real theta)  
{
    TMReal  c, s;
    
    SetReal(s, sin(theta));
    SetReal(c, cos(theta));
    
#ifdef VL_ROW_ORIENT
    row[0][0] =  c; row[0][1] = s;
    row[1][0] = -s; row[1][1] = c;
#else
    row[0][0] = c; row[0][1] = -s;
    row[1][0] = s; row[1][1] =  c;
#endif

    return(SELF);
}

TMat2 &TMat2::MakeScale(const TMVec2 &s)
{       
    row[0][0] = s[0]; row[0][1] = vl_0;
    row[1][0] = vl_0; row[1][1] = s[1];
    
    return(SELF);
}

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