一直不知道怎么解决的问题,lisp 值的范围,最大值

挚友01

将(setq a 99999999) 返回a=99999999   当 (setq a 99999999999999999) a就返回科学计数, (+ a 1) 值就错了,LISP好象超出计算范围了,一直不知道怎么解决的问题,求助!!!!!!!!!!!

newer

整数受CPU的整数位数限制，大小都有限制的，你改成浮点数不就行了。

挚友01

lisp 没有对数据进行定义啊...

XDSoft

挚友01 发表于 2014-11-15 21:08
lisp 没有对数据进行定义啊...

你加小数点不就行啦。

挚友01

加小数点了,也没用啊,, (setq a 99999999999.9) !a=1.0e+011

挚友01

???????????

st788796

挚友01 发表于 2014-11-17 09:59
???????????

Autolisp 联机帮助中 AutoLISP Data Types 这样描述 Intergers

Integers are whole numbers that do not contain a decimal point. AutoLISP integers are 32-bit signed numbers with values ranging from +2,147,483,647 to -2,147,483,648. (Note, however, that the getint function only accepts 16-bit numbers ranging from +32767 to -32678.) When you explicitly use an integer in an AutoLISP expression, that value is known as a constant. Numbers such as 2, -56, and 1,200,196 are valid AutoLISP integers.

If you enter a number that is greater than the maximum integer allowed (resulting in integer overflow), AutoLISP converts the integer to a real number. However, if you perform an arithmetic operation on two valid integers, and the result is greater than the maximum allowable integer, the resulting number will be invalid. The following examples illustrate how AutoLISP handles integer overflow.

The largest positive integer value retains its specified value:

_$ 2147483647
2147483647
If you enter an integer that is greater than the largest allowable value, AutoLISP returns the value as a real:

_$ 2147483648
2.14748e+009
An arithmetic operation involving two valid integers, but resulting in integer overflow, produces an invalid result:

_$ (+ 2147483646 3)
-2147483647
In this example the result is clearly invalid, as the addition of two positive numbers results in a negative number. But note how the following operation produces a valid result:

_$ (+ 2147483648 2)
2.14748e+009
In this instance, AutoLISP converts 2147483648 to a valid real before adding 2 to the number. The result is a valid real.

The largest negative integer value retains its specified value:

挚友01

英文不好,看不太明白,怎么解决?

挚友01

??????????????????

挚友01

有没有什么办法?

st788796

挚友01 发表于 2014-11-20 20:42
有没有什么办法?

你要解决什么?
_$ (setq a 99999999999.9)
1.0e+011
_$ (rtos a 2 15)
"99999999999.9"
_$

挚友01

(setq a 99999999999.9) =1.0e+011
(+ a 1) = 错误的值           计算后不等于想要的值了...  

st788796

挚友01 发表于 2014-11-22 08:00
(setq a 99999999999.9) =1.0e+011
(+ a 1) = 错误的值           计算后不等于想要的值了...

眼见不一定为，瞎操心

_$ (setq a 99999999999.9)
1.0e+011
_$ (+ a 1)
1.0e+011
_$ (rtos (+ a 1) 2 12)
"100000000000.9"
_$

jinbin2008a

:)求好的LISP

挚友01

(setq a 9999999999.9)
(command "line" b (polar b 0 a) "")
(command "line" b (polar b 0 (+ a 1000)) "")
两条线是一样的长度啊...怎么解释?