精度 num2string matlab
precision num2string matlab
我有一些关于 MatLab 中 num2str() fctn 精度的问题。
a=0.11111111111111;
b=a;
Linux/OSX: num2str(a+b,25): ans=0.2222222222222221655465116
Windows: num2str(a+b,25): ans= 0.222222222222222
谁能解释一下使用 Linux/OSX 系统时小数点后第 15 位的数字是从哪里来的？ num2str() 可以获得的最大精度是多少？
num2str 文档中有一些我不完全理解的提示。
Note: If you specify precision to exceed the precision of the input floating-point data type, the results might not match the input values to the precision you specified. The result depends on your computer hardware and operating system.
查看 eps (https://de.mathworks.com/help/matlab/ref/eps.html)，它为您提供浮点相对精度，这取决于您的系统架构。
在这里进一步查看：https://de.mathworks.com/matlabcentral/answers/26458-machine-epsilon:
It roughly means that numbers are stored with about 15-16 digits of
precision. If a number is approximately 1, then that means it can be
stored with an error of around 10^(-16)
[...]
d = eps(X) is the positive distance from abs(X) to the next larger in
magnitude floating point number of the same precision as X"
That says that d = eps(1) is the smallest positive value such that
(1+d) is exactly representable and is different than 1.
1+eps(1) is the smallest representable number greater than 1, a single
bit difference in the least significant (smallest change) bit.
也可以在此处查看以大致了解更多信息（因为它并不是真正的 MATLAB 特定主题）：https://en.wikipedia.org/wiki/Machine_epsilon
我有一些关于 MatLab 中 num2str() fctn 精度的问题。
a=0.11111111111111;
b=a;
Linux/OSX: num2str(a+b,25): ans=0.2222222222222221655465116
Windows: num2str(a+b,25): ans= 0.222222222222222
谁能解释一下使用 Linux/OSX 系统时小数点后第 15 位的数字是从哪里来的？ num2str() 可以获得的最大精度是多少？
num2str 文档中有一些我不完全理解的提示。
Note: If you specify precision to exceed the precision of the input floating-point data type, the results might not match the input values to the precision you specified. The result depends on your computer hardware and operating system.
查看 eps (https://de.mathworks.com/help/matlab/ref/eps.html)，它为您提供浮点相对精度，这取决于您的系统架构。
在这里进一步查看：https://de.mathworks.com/matlabcentral/answers/26458-machine-epsilon:
It roughly means that numbers are stored with about 15-16 digits of precision. If a number is approximately 1, then that means it can be stored with an error of around 10^(-16)
[...]
d = eps(X) is the positive distance from abs(X) to the next larger in magnitude floating point number of the same precision as X"
That says that d = eps(1) is the smallest positive value such that (1+d) is exactly representable and is different than 1.
1+eps(1) is the smallest representable number greater than 1, a single bit difference in the least significant (smallest change) bit.
也可以在此处查看以大致了解更多信息（因为它并不是真正的 MATLAB 特定主题）：https://en.wikipedia.org/wiki/Machine_epsilon