.\"
.de Id
..
.de Sp
.if n .sp
.if t .sp 0.4
..
.TH eye 2rheolef "rheolef-6.5" "rheolef-6.5" "rheolef-6.5"
.\" label: /*Class:eye
.SH NAME
\fBeye\fP - the identity matrix
.SH DESCRIPTION

Following matlab, the name \fBeye()\fP is used in place of I to denote identity matrices
because I is often used as a subscript or as sqrt(-1). The dimensions of \fBeye()\fP are
determined by context.
The preconditioner interface is usefull when calling algorithms without any
preconditioners, e.g.
.\" begin_example
.Sp
.nf
    int status = pcg (a, x, b, eye(), 100, 1e-7);
.Sp
.fi
.\" end_example
.\" skip start:AUTHOR:

.\" skip start:DATE:

.\" END
.SH IMPLEMENTATION
.\" begin_example
.Sp
.nf
class eye {
public:
  eye() {}
  template<class T> const vec<T>& operator* (const vec<T>& x) const { return x; }
  template<class T> const vec<T>& solve (const vec<T>& x) const { return x; }
  template<class T> const vec<T>& trans_solve (const vec<T>& x) const { x; }
};
.Sp
.fi
.\" end_example