Interpolate the same data with Mathematica 5.2, 7.0.1 and 8.0.1:
Interpolation[{{0, 0}, {1, 1}, {2, 3}, {3, 4}, {4, 3}, {5, 0}}]
Outputs:
Mathematica 5.2:
InterpolatingFunction[{{0, 5}}, {2, 0, True, False, {3}, {0}}, {{0, 1, 2, 3, 4, 5}}, {{0}, {1}, {3}, {4}, {3}, {0}}, {Automatic}]
Mathematica 7.0.1:
InterpolatingFunction[{{0, 5}}, {3, 1, 0, {6}, {4}, 0, 0, 0, 0}, {{0, 1, 2, 3, 4, 5}}, {{0}, {1}, {3}, {4}, {3}, {0}}, {Automatic}]
Mathematica 8.0.1:
InterpolatingFunction[{{0, 5}}, {4, 3, 0, {6}, {4}, 0, 0, 0, 0, Automatic}, {{0, 1, 2, 3, 4, 5}}, {{0}, {1}, {3}, {4}, {3}, {0}}, {Automatic}]
Mathematica 5.2 output still works when used as an input in version 7.0.1, but not version 8.0.1. It seems that the old-style support for InterpolatingFunction was removed in version 8. Is it possible to reuse the InterpolatingFunction data created by Mathematica 5.2 in version 8.0.1?