fix issues of denormal inconsistency in purification #805

Job	Run time
bld (linux_release_64, ubuntu-20.04, -release_64, -asm)	1s
vis	1s
bld (linux_debug_64, ubuntu-20.04, -debug_64)	1s
format_clang	1s
bld (mac_release_64, macos-13, -release_64, -asm)	1s
bld (mac_debug_64, macos-13, -debug_64)	1s
format_ruff	1s
bld (mac_release_arm, macos-14, -release_arm, -asm)	1s
sdist	1s
bld (mac_debug_arm, macos-14, -debug_arm)	23s
bld (win_release_64, windows-2022, -release_64)	1s
bld (win_debug_64, windows-2022, -debug_64)	1s
testS	1s
docs	1s
testC	1s
bdist	1s
powerlift	1s
R	1s
npm	1s
testB	1s
test_powerlift	1s
testR	1s
	44s

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