Hi,
I'm sorry if this question has been asked before but I couldn't find any appropriate answer elsewhere and hence this post. Today while doing some calculation using bc I found a very peculiar thing. I was performing an operation -2 % -3 and the software reported the answer as -2. Now -2 > -3 and if I remember correctly then in divison operation the remainder is less than the divisor. So how come in this case the answer is not coming properly. Is it a software flaw or there is some mistake in my understanding of the division operation ?
Thanks and regards,
Mayank
On Thu, Jun 18, 2009 at 9:03 AM, Mayank wrote:
I'm sorry if this question has been asked before but I couldn't find any appropriate answer elsewhere and hence this post. Today while doing some calculation using bc I found a very peculiar thing. I was performing an operation -2 % -3 and the software reported the answer as -2. Now -2 > -3 and if I remember correctly then in divison operation the remainder is less than the divisor. So how come in this case the answer is not coming properly. Is it a software flaw or there is some mistake in my understanding of the division operation ?
From the bc man page:
"expr % expr The result of the expression is the "remainder" and it is computed in the following way. To compute a%b, first a/b is computed to scale digits. That result is used to compute a-(a/b)*b to the scale of the maximum of scale+scale(b) and scale(a). If scale is set to zero and both expressions are integers this expression is the integer remainder function."
Now, the default "scale" in bc is 0, which takes all fractions to the integer preceding them. e.g. -- Kumar
Sorry, I clicked sent before completing the mail!
On Thu, Jun 18, 2009 at 9:07 AM, Kumar Appaiah kumar.appaiah@gmail.com wrote:
On Thu, Jun 18, 2009 at 9:03 AM, Mayank wrote:
I'm sorry if this question has been asked before but I couldn't find any appropriate answer elsewhere and hence this post. Today while doing some calculation using bc I found a very peculiar thing. I was performing an operation -2 % -3 and the software reported the answer as -2. Now -2 > -3 and if I remember correctly then in divison operation the remainder is less than the divisor. So how come in this case the answer is not coming properly. Is it a software flaw or there is some mistake in my understanding of the division operation ?
From the bc man page:
"expr % expr The result of the expression is the "remainder" and it is computed in the following way. To compute a%b, first a/b is computed to scale digits. That result is used to compute a-(a/b)*b to the scale of the maximum of scale+scale(b) and scale(a). If scale is set to zero and both expressions are integers this expression is the integer remainder function."
Now, the default "scale" in bc is 0, which takes all fractions to the integer preceding them. e.g.
-- Kumar
On Thu, Jun 18, 2009 at 9:08 AM, Kumar Appaiah wrote:
Sorry, I clicked sent before completing the mail!
OK, there really is a keyboard fault here. Sorry about this!
On Thu, Jun 18, 2009 at 9:07 AM, Kumar Appaiah kumar.appaiah@gmail.com wrote:
On Thu, Jun 18, 2009 at 9:03 AM, Mayank wrote:
I'm sorry if this question has been asked before but I couldn't find any appropriate answer elsewhere and hence this post. Today while doing some calculation using bc I found a very peculiar thing. I was performing an operation -2 % -3 and the software reported the answer as -2. Now -2 > -3 and if I remember correctly then in divison operation the remainder is less than the divisor. So how come in this case the answer is not coming properly. Is it a software flaw or there is some mistake in my understanding of the division operation ?
From the bc man page:
"expr % expr The result of the expression is the "remainder" and it is computed in the following way. To compute a%b, first a/b is computed to scale digits. That result is used to compute a-(a/b)*b to the scale of the maximum of scale+scale(b) and scale(a). If scale is set to zero and both expressions are integers this expression is the integer remainder function."
Now, the default "scale" in bc is 0, which takes all fractions to the integer preceding them. e.g. 15/8 evaluates to 1. Now, try your expression. -2/-3 is 0, then -2 - (-2/-3)*-3 is -2. So that is what you get, right?
Now, it isn't the remainder function, but then, it does what is advertised, I guess.
HTH, and sorry for 3 mails. :-(
Kumar -- Kumar
On Thu, Jun 18, 2009 at 6:41 PM, Kumar Appaiah kumar.appaiah@gmail.comwrote:
From the bc man page:
"expr % expr The result of the expression is the "remainder" and it is computed in the following way. To compute a%b, first a/b is computed to scale digits. That result is used to compute a-(a/b)*b to the scale of the maximum of scale+scale(b) and scale(a). If scale is set to zero and both expressions are integers this expression is the integer remainder function."
Now, the default "scale" in bc is 0, which takes all fractions to the integer preceding them. e.g. 15/8 evaluates to 1. Now, try your expression. -2/-3 is 0, then -2 - (-2/-3)*-3 is -2.
Thanks for the explanation of how bc does the job of calculating the remainder.
Mayank
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Kumar Appaiah -
Mayank