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Turnbull China Bikeride
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Turnbull China Bikeride - Disc 1.iso
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hankel
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1994-02-21
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1KB
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57 lines
//-------------------------------------------------------------------//
// Syntax: hankel ( C )
// hankel ( C , R )
// Description:
// Hankel(C) is a square Hankel matrix whose first column is C and
// whose elements are zero below the first anti-diagonal.
// Hankel(C,R) is a Hankel matrix whose first column is C and whose
// last row is R.
// Hankel matrices are symmetric, constant across the anti-diagonals,
// and have elements H[i;j] = R[i+j-1].
// See also toeplitz.r.
//-------------------------------------------------------------------//
hankel = function ( c_ , r_ )
{
local(c, r, nc, h, j, nr);
if (class(c_) != "num") { error("hankel: Input must be numeric"); }
c = c_[:];
nc = length (c);
if (!exist (r_))
{
h = zeros (nc, nc);
for (j in 1:nc)
{
h[1:nc-j+1;j] = c[j:nc];
}
else
if (class (r_) != "num") { error("hankel: Inputs must be numeric"); }
if (length(c_) != length(r_))
{
error("hankel: Inputs must have the same length");
}
r = r_[:];
nr = length (r);
h = zeros (nc, nr);
if (c[nc] != r[1])
{
error("hankel: First element of row must match last element of column");
}
for (j in 1:nc-1)
{
h[;j] = [c[j:nc-1]; r[1:j]];
}
h[;nc] = r;
}
return h;
};