var r Rat
		if r2 := r.SetFloat64(f); r2 != nil {
			t.Errorf("SetFloat64(%g) was %v, want nil", f, r2)
		}
	}
}

// checkNonLossyRoundtrip32 checks that a float->Rat->float roundtrip is
// non-lossy for finite f.
func checkNonLossyRoundtrip32(t *testing.T, f float32) {
	if !isFinite(float64(f)) {
		return
	}
	r := new(Rat).SetFloat64(float64(f))
	if r == nil {

		if !checkIsBestApprox32(t, f, r) {
			// Append context information.
			t.Errorf("(input was %q)", input)
		}

		// 3. Check f->R->f roundtrip is non-lossy.
		checkNonLossyRoundtrip32(t, f)

		// 4. Check exactness using slow algorithm.
		if wasExact := new(Rat).SetFloat64(float64(f)).Cmp(r) == 0; wasExact != exact {