All sse single - precision operations will , however , use a 24 - bit significand 8 - bit exponent , and sse2 double - precision operations will use a 53 - bit significand 11 - bit exponent 但是,所有sse單精度運算都將使用24位有效數(shù)/ 8位指數(shù),而sse2雙精度運算將使用53位有效數(shù)/ 11位指數(shù)。
To modify the fp control word , then the run - time startup code will set the x87 fpu control word precision - control field to 53 - bits , so all float and double operations within an expression will occur with 53 - bit significand and 15 - bit exponent 修改fp控制字,則運行庫啟動代碼會將x87 fpu控制字精度控制字段設(shè)置為53位,這樣,表達式內(nèi)的所有浮點運算和雙精度運算都以53位有效數(shù)和15位指數(shù)進行。