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<HTML><HEAD><TITLE>Newmat09 - scalar functions of a matrix</TITLE></HEAD><BODY><H2>Scalar functions of a matrix</H2><A HREF="submat.html"> next</A> - <A HREF="submat.html"> skip</A> - <A HREF="refer.html"> up</A> - <A HREF="index.html"> start</A><P><PRE> int m = A.Nrows(); // number of rows int n = A.Ncols(); // number of columns Real r = A.AsScalar(); // value of 1x1 matrix Real ssq = A.SumSquare(); // sum of squares of elements Real sav = A.SumAbsoluteValue(); // sum of absolute values Real s = A.Sum(); // sum of values Real mav = A.MaximumAbsoluteValue(); // maximum of absolute values Real norm = A.Norm1(); // maximum of sum of absolute values of elements of a column Real norm = A.NormInfinity(); // maximum of sum of absolute values of elements of a row Real t = A.Trace(); // trace LogAndSign ld = A.LogDeterminant(); // log of determinant bool z = A.IsZero(); // test all elements zero MatrixType mt = A.Type(); // type of matrix Real* s = Store(); // pointer to array of elements int l = Storage(); // length of array of elements bool s = A.IsSingular(); // A is a CroutMatrix or BandLUMatrix MatrixBandWidth mbw = A.BandWidth(); // upper and lower bandwidths</PRE><TT>A.LogDeterminant()</TT> returns a value of type LogAndSign.If ld is of type LogAndSign use<PRE> ld.Value() to get the value of the determinant ld.Sign() to get the sign of the determinant (values 1, 0, -1) ld.LogValue() to get the log of the absolute value.</PRE><TT>A.IsZero()</TT> returns Boolean value <TT>true</TT>if the matrix <TT>A</TT>has all elements equal to 0.0.<P><TT>IsSingular</TT> is defined only for CroutMatrix and BandLUMatrix. It returns<TT>true</TT> if one of the diagonal elements of the LU decomposition isexactly zero. <P><TT>MatrixType mt = A.Type()</TT> returns the type of a matrix.Use <TT>(char*)mt</TT> toget a string (UT, LT, Rect, Sym, Diag, Band, UB, LB, Crout, BndLU)showing the type(Vector types are returned as Rect).<P><TT>MatrixBandWidth</TT> has member functions <TT>Upper()</TT> and<TT>Lower()</TT> for finding the upper and lower bandwidths (number of diagonalsabove and below the diagonal, both zero for a diagonal matrix). For non-bandmatrices -1 is returned for both these values.<P>The versionsSum(A), SumSquare(A), SumAbsoluteValue(A), MaximumAbsoluteValue(A), Trace(A),LogDeterminant(A), Norm1(A), NormInfinity(A) can be used in place ofA.Sum(), A.SumSquare(), A.SumAbsoluteValue(), A.MaximumAbsoluteValue(),A.Trace(), A.LogDeterminant(), A.Norm1(), A.NormInfinity().<P><A HREF="submat.html"> next</A> - <A HREF="submat.html"> skip</A> - <A HREF="refer.html"> up</A> - <A HREF="index.html"> start</A><P></BODY></HTML>?? 快捷鍵說明
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