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64 lines
1.8 KiB
Mathematica
64 lines
1.8 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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%
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% Test that we roundtrip floats.
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%
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:- module float_roundtrip.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module int.
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:- import_module list.
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:- import_module string.
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main(!IO) :-
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test_float(7, 0.9092974, !IO),
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test_float(9, 0.123573124, !IO),
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test_float(15, 0.987654321012345, !IO),
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test_float(17, 0.12345678901234566, !IO),
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test_float_roundtrippable(1.8e-10, !IO).
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:- pred test_float(int::in, float::in, io::di, io::uo) is det.
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test_float(ReqPrecision, Float, !IO) :-
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FloatStr =
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string.format("%." ++ int_to_string(ReqPrecision) ++ "g", [f(Float)]),
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Precision = string.length(FloatStr) - 2,
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io.format("%-20s: ", [s(FloatStr)], !IO),
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( if Precision = ReqPrecision then
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( if roundtrip_float(Float) then
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io.write_string("success.\n", !IO)
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else
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io.write_string("failed.\n", !IO)
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)
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else
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io.write_string("failed as only ", !IO),
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io.write_int(Precision, !IO),
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io.write_string(" digits of precision.\n", !IO)
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).
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:- pred test_float_roundtrippable(float::in, io::di, io::uo) is det.
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test_float_roundtrippable(Flt, !IO) :-
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( if roundtrip_float(Flt) then
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io.format("%-20s: ", [s(string.float_to_string(Flt))], !IO),
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io.write_string("success.\n", !IO)
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else
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io.format("failed to roundtrip %f\n", [f(Flt)], !IO)
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).
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% Test that when we round-trip the float, we get the same float back.
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%
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:- pred roundtrip_float(float::in) is semidet.
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roundtrip_float(Float) :-
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float_to_string(Float, String),
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string.to_float(String, Float).
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