Rem Problem

[prakashreddy]

Rem is working different different or i may understood wrong

 

(rem 1262.8 180.4)
180.4

 

(rem 4.2 2.1)
0.0

 

 

Can any clear me

[Stefan BMR]

Divides the first number by the second, and returns the remainder

For any A and B, A=n*B+R, where n is the largest possible integer and R is the remainder.

In your sample 1262.8 = 7 * 180.4 + 0 and it should return 0.0

The trouble with reals is that they are always truncated, so what you think is 180.4 is in fact 180.399999999....

_$ (rtos (rem 1262.8 180.4) 2 16)
"180.3999999999999"
_$ 

[Lee Mac]

As Stefan has correctly pointed out, given that reals (doubles) cannot be represented exactly (since this would require infinite memory), tolerances must be applied when working with reals.

 

Hence, if you are looking to test for even divisibility of two reals, an alternative solution might be:

(defun divisible-p ( n d / r )
   (setq r (rem n d))
   (or (equal r 0.0 1e- (equal r d 1e-)
)

_$ (divisible-p 1262.8 180.4)
T

Here, a tolerance of 1e-8 (0.00000001) has been used.

[prakashreddy]

(/= 0 (rem (* 100 (- 1443.60 180.80)) (* 100 180.4)))

 

 

Is there any other way to resolve it...

[prakashreddy]

Thanks Mr Stefan & Mr Lee for your information.

[Lee Mac]

Thanks Mr Stefan & Mr Lee for your information.

 

You're very welcome.

On this topic, you may want to read this article.