Singular

LIB "chern.lib";
// the terms of the Todd class up to degree 5
// in terms of the Chern classes c(1), c(2), c(3), c(4), c(5)
ring r=0, (c(1..5)), dp;
list l=c(1..5);
print( todd( l ) );
==> [1]:
==>    1/2*c(1)
==> [2]:
==>    1/12*c(1)^2+1/12*c(2)
==> [3]:
==>    1/24*c(1)*c(2)
==> [4]:
==>    -1/720*c(1)^4+1/180*c(1)^2*c(2)+1/240*c(2)^2+1/720*c(1)*c(3)-1/720*c(4\
   )
==> [5]:
==>    -1/1440*c(1)^3*c(2)+1/480*c(1)*c(2)^2+1/1440*c(1)^2*c(3)-1/1440*c(1)*c\
   (4)
// in the same situation compute only first two terms
print( todd(l, 2) );
==> [1]:
==>    1/2*c(1)
==> [2]:
==>    1/12*c(1)^2+1/12*c(2)
// compute the first 5 terms corresponding to the Chern clases c(1), c(2)
l=c(1..2);
print( todd(l, 5) );
==> [1]:
==>    1/2*c(1)
==> [2]:
==>    1/12*c(1)^2+1/12*c(2)
==> [3]:
==>    1/24*c(1)*c(2)
==> [4]:
==>    -1/720*c(1)^4+1/180*c(1)^2*c(2)+1/240*c(2)^2
==> [5]:
==>    -1/1440*c(1)^3*c(2)+1/480*c(1)*c(2)^2