Prev: Newbie question: delete newline character with sed
Next: How to sum csv column data in ksh
From: BJ on 28 Aug 2006 04:53
I'm trying to get two (2) decimal places in the code below with an
accurate number of "43.21", but I only get "43.00". If I change
"scale=2" to "scale=4", I get "43.2100".

What do I need to do to get an output of "43.21"? Thanks.

#!/bin/bash
TOP=4321.0
BOTTOM=10000.0
RESULT=$(echo "scale=2;$TOP/$BOTTOM*100"|bc)

echo $RESULT

From: Eric Moors on 28 Aug 2006 06:20
BJ wrote:

> echo "scale=2;$TOP/$BOTTOM*100"|bc

your $TOP/$BOTTOM requires 4 digits accuracy.

so try:
echo "scale=2;100*$TOP/$BOTTOM"|bc

Eric
From: BJ on 28 Aug 2006 07:25
> > echo "scale=2;$TOP/$BOTTOM*100"|bc
>
> your $TOP/$BOTTOM requires 4 digits accuracy.
>
> so try:
> echo "scale=2;100*$TOP/$BOTTOM"|bc
>
> Eric

Thanks! That did it, but why did moving the "100" in front of the
division make a difference?

From: Eric Moors on 28 Aug 2006 08:05
BJ wrote:

>> > echo "scale=2;$TOP/$BOTTOM*100"|bc
>>
>> your $TOP/$BOTTOM requires 4 digits accuracy.
>>
>> so try:
>> echo "scale=2;100*$TOP/$BOTTOM"|bc
>>
>> Eric
>
> Thanks! That did it, but why did moving the "100" in front of the
> division make a difference?

Like I mentioned $TOP/$BOTTOM (4321/10000) requires 4 digits accuracy
as it results to 0.4321. If you choose scale=2, it is trimmed down to
0.43. Then the multiplication with 100 takes place, resulting into 43.00
Moving 100 to the front results in (100*4321)/10000 = 432100/10000 = 43.21
So not using more then 2 digits of accuracy here doesn't loose info.

Eric
From: Jon LaBadie on 28 Aug 2006 11:50
Eric Moors wrote:
> BJ wrote:
>
>>>> echo "scale=2;$TOP/$BOTTOM*100"|bc
>>> your $TOP/$BOTTOM requires 4 digits accuracy.
>>>
>>> so try:
>>> echo "scale=2;100*$TOP/$BOTTOM"|bc
>>>
>>> Eric
>> Thanks! That did it, but why did moving the "100" in front of the
>> division make a difference?
>
> Like I mentioned $TOP/$BOTTOM (4321/10000) requires 4 digits accuracy
> as it results to 0.4321. If you choose scale=2, it is trimmed down to
> 0.43. Then the multiplication with 100 takes place, resulting into 43.00
> Moving 100 to the front results in (100*4321)/10000 = 432100/10000 = 43.21
> So not using more then 2 digits of accuracy here doesn't loose info.
>

Any way to have internal calculations done to higher precision but
presented with lower? Aside from something like:
scale = 20; <calc> ; scale = 2 ; . * 1
 |  Next  |  Last
Pages: 1 2
Prev: Newbie question: delete newline character with sed
Next: How to sum csv column data in ksh