x87

问题 If I have 2 denormal floating point numbers with different bit patterns and compare them for equality, can the result be affected by the Denormals-Are-Zero flag, the Flush-to-Zero flag, or other flags on commonly used processors? Or do these flags only affect computation and not equality checks? 回答1: DAZ (Denormals Are Zero) affects reading input, so DAZ affects compares . All denormals are literally treated as -0.0 or +0.0 , according to their sign. FTZ (Flush To Zero) affects only writing

问题 If I have 2 denormal floating point numbers with different bit patterns and compare them for equality, can the result be affected by the Denormals-Are-Zero flag, the Flush-to-Zero flag, or other flags on commonly used processors? Or do these flags only affect computation and not equality checks? 回答1: DAZ (Denormals Are Zero) affects reading input, so DAZ affects compares . All denormals are literally treated as -0.0 or +0.0 , according to their sign. FTZ (Flush To Zero) affects only writing

问题 Good afternoon! In this example, I simply add two numbers with a comma, save the variable in tbyte and display the same variable two times in a row on the screen, but the first time I get 11.1 , as it should be, and the second time 4.667261E-062 . Why is this happening? And one more question, is it possible in tbyte to somehow save and access numbers by array type? for example, storing numbers in dd , I just could save and read them in increments of 4, for example, result [0] , result [4] ,

问题 Is there any way to get correct rounding with the i387 fsqrt instruction?... ... aside from changing the precision mode in the x87 control word - I know that's possible, but it's not a reasonable solution because it has nasty reentrancy-type issues where the precision mode will be wrong if the sqrt operation is interrupted. The issue I'm dealing with is as follows: the x87 fsqrt opcode performs a correctly-rounded (per IEEE 754) square root operation in the precision of the fpu registers,

问题 Is there any way to get correct rounding with the i387 fsqrt instruction?... ... aside from changing the precision mode in the x87 control word - I know that's possible, but it's not a reasonable solution because it has nasty reentrancy-type issues where the precision mode will be wrong if the sqrt operation is interrupted. The issue I'm dealing with is as follows: the x87 fsqrt opcode performs a correctly-rounded (per IEEE 754) square root operation in the precision of the fpu registers,

问题 I got these GCC flags from the GNU GCC compiler Manual. But when I tried to use those flags ( -mpc32 , -mpc64 and -mpc80 ) I couldn't observe the behavior. So I need help on how to use these flags with a sample code. sample code I tried: test.cpp #include<stdio.h> #include<iomanip> #include<math.h> int main() { double weight = 1.0f; double roiSize = 137.142364501953125f; double thresholdValue = 5400.0f; double alpha = weight / (roiSize * thresholdValue * thresholdValue); std::cout<<std:

问题 I got these GCC flags from the GNU GCC compiler Manual. But when I tried to use those flags ( -mpc32 , -mpc64 and -mpc80 ) I couldn't observe the behavior. So I need help on how to use these flags with a sample code. sample code I tried: test.cpp #include<stdio.h> #include<iomanip> #include<math.h> int main() { double weight = 1.0f; double roiSize = 137.142364501953125f; double thresholdValue = 5400.0f; double alpha = weight / (roiSize * thresholdValue * thresholdValue); std::cout<<std:

问题 I got these GCC flags from the GNU GCC compiler Manual. But when I tried to use those flags ( -mpc32 , -mpc64 and -mpc80 ) I couldn't observe the behavior. So I need help on how to use these flags with a sample code. sample code I tried: test.cpp #include<stdio.h> #include<iomanip> #include<math.h> int main() { double weight = 1.0f; double roiSize = 137.142364501953125f; double thresholdValue = 5400.0f; double alpha = weight / (roiSize * thresholdValue * thresholdValue); std::cout<<std:

问题 I got these GCC flags from the GNU GCC compiler Manual. But when I tried to use those flags ( -mpc32 , -mpc64 and -mpc80 ) I couldn't observe the behavior. So I need help on how to use these flags with a sample code. sample code I tried: test.cpp #include<stdio.h> #include<iomanip> #include<math.h> int main() { double weight = 1.0f; double roiSize = 137.142364501953125f; double thresholdValue = 5400.0f; double alpha = weight / (roiSize * thresholdValue * thresholdValue); std::cout<<std:

问题 I got these GCC flags from the GNU GCC compiler Manual. But when I tried to use those flags ( -mpc32 , -mpc64 and -mpc80 ) I couldn't observe the behavior. So I need help on how to use these flags with a sample code. sample code I tried: test.cpp #include<stdio.h> #include<iomanip> #include<math.h> int main() { double weight = 1.0f; double roiSize = 137.142364501953125f; double thresholdValue = 5400.0f; double alpha = weight / (roiSize * thresholdValue * thresholdValue); std::cout<<std: