将无穷大转换为零 [英] Convert infinity to zero
问题描述
我有一个代码，在程序的某些部分计算1 / x的
很多不同的x'。大约100次x中的1次等于零，所以当
我打印结果时我获得了inf。我想知道是否有办法检测这个无穷大的价值。并将其转换为浮点零。我的意思是
喜欢
for i = ....
计算1 / x_i
如果x_i = inf则x_i = 0.
....
谢谢
Hi,
I have a code that in some part of the program calculates 1/x for a
lot of different x''s. About 1 of 100 times x is equal to zero, so when
I print the result I obtain inf. I wonder if there is a way to detect
this "infinity" and convert it to the float zero. I mean something
like
for i = ....
calculate 1/x_i
if x_i = inf then x_i = 0.
....
Thanks
推荐答案
在文章< 11 ********************* @ y80g2000hsf.googlegroups中。 com>，
< ho ********** @ gmail.comwrote：
In article <11*********************@y80g2000hsf.googlegroups. com>,
<ho**********@gmail.comwrote:
>
我有一个代码，在程序的某些部分计算1 / x用于许多不同的x'。大约100次x中的1次等于零，所以当我打印结果时我获得了inf。我想知道是否有办法检测这个无穷大的情况。并将其转换为浮点零。我的意思是
对于i = ....
计算1 / x_i
如果x_i = inf则x_i = 0.
....
>Hi,
I have a code that in some part of the program calculates 1/x for a
lot of different x''s. About 1 of 100 times x is equal to zero, so when
I print the result I obtain inf. I wonder if there is a way to detect
this "infinity" and convert it to the float zero. I mean something
like
for i = ....
calculate 1/x_i
if x_i = inf then x_i = 0.
....
--------
if（fabs（ x_i）< epsilon）
{
/ *处理1 / x_i的坏值* /
}
另外
{
/ *做1 / x_i * /
的东西}
---- ----
这取决于你在做什么结果，但我不会惊讶
如果将INF折叠为0是错误的方式处理坏的价值。
dave
-
Dave Vandervies dj ****** @ csclub.uwaterloo.ca
我打赌我的一半CD来自现已不再出售的商店商业。这是一件好事，他们不需要每90天给家里打电话来保持工作，真的。 - 彼得·科莱特在可怕的魔鬼修道院中
--------
if(fabs(x_i) < epsilon)
{
/*handle bad value for 1/x_i*/
}
else
{
/*do stuff with 1/x_i*/
}
--------
It depends what you''re doing with the result, but I would be unsurprised
if folding INF to 0 is the wrong way to handle bad values.
dave
--
Dave Vandervies dj******@csclub.uwaterloo.ca
I bet half of my CDs are from shops that are now no longer in business. It''s
a good thing that they don''t need to phone home every 90 days to keep
working, really. --Peter Corlett in the scary devil monastery
ho * *********@gmail.com 写道：
我有一个代码，在程序的某些部分计算1 / x的
很多不同的x'。大约100次x中的1次等于零，所以当
我打印结果时我获得了inf。我想知道是否有办法检测这个无穷大的价值。并将其转换为浮点零。我的意思是
喜欢
for i = ....
计算1 / x_i
如果x_i = inf则x_i = 0.
....
Hi,
I have a code that in some part of the program calculates 1/x for a
lot of different x''s. About 1 of 100 times x is equal to zero, so when
I print the result I obtain inf. I wonder if there is a way to detect
this "infinity" and convert it to the float zero. I mean something
like
for i = ....
calculate 1/x_i
if x_i = inf then x_i = 0.
....
这是一个C新闻组;张贴不完整的伪代码不一定
得到你想要的答案。
怎么样
#include< math.h> ;
.....
if（isinf（x_i））{
//做你想做的事
}
由于所有旧的编译器和库都不支持，你可能需要提供自己版本的这个函数。它可能很简单
#include< math.h>
#include< float.h>
int（isinf） （双x）{
返回x DBL_MAX || x< -DBL_MAX;
}
当然你可以从常见问题解答中学到一些东西。
This is a C newsgroup; posting incomplete pseudo-code won''t necessarily
get you the answer you wanted.
How about
#include <math.h>
.....
if( isinf(x_i) ) {
//do whatever you wish
}
As this won''t be supported by all older compilers and libraries, you may
have to provide your own version of this function. It may be as simple as
#include <math.h>
#include <float.h>
int (isinf)(double x){
return x DBL_MAX || x < -DBL_MAX ;
}
Surely you could have learned something from FAQs.
ho ********** @ gmail.com 写道：
我有一个代码，在程序的某些部分计算1 / x的
很多不同的x''秒。大约100次x中的1次等于零，所以当
我打印结果时我获得了inf。我想知道是否有办法检测这个无穷大的价值。并将其转换为浮点零。我的意思是
喜欢
for i = ....
计算1 / x_i
如果x_i = inf则x_i = 0.
....
Hi,
I have a code that in some part of the program calculates 1/x for a
lot of different x''s. About 1 of 100 times x is equal to zero, so when
I print the result I obtain inf. I wonder if there is a way to detect
this "infinity" and convert it to the float zero. I mean something
like
for i = ....
calculate 1/x_i
if x_i = inf then x_i = 0.
....
当没有理由测试错误的结果时你可以在第一时间避免错误。
明显的
如果（！x）{有什么问题？ / *处理零* /}
是你感兴趣的是x足够的情况
小：
const almost_zero; / *为此分配适当的值* /
/& ...... * /
if（fabs（x）< almost_zero）{/&处理接近零* / |
There is no reason to test the result of a mistake when you can avoid
the mistake in the first place.
What is wrong with the obvious
if (!x) { /* handle zero */ }
is that what you are interested in is the case where x is sufficiently
small:
const almost_zero; /* assign an appropriate value to this */
/& ... */
if (fabs(x) < almost_zero) { /& handle near zero */ |
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