|  |  D.3.1.27 headStand Procedure from librarymatrix.lib(see  matrix_lib).
 
Example:Usage:
headStand(M); M matrix
Return:
matrix B such that B[i][j]=M[n-i+1,m-j+1], n=nrows(M), m=ncols(M)
 |  | LIB "matrix.lib";
ring r=0,(A,B,C),dp;
matrix M[2][3]=
0,A,  B,
A2, B2, C;
print(M);
==> 0, A, B,
==> A2,B2,C 
print(headStand(M));
==> C,B2,A2,
==> B,A, 0  
 | 
 
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