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Float operation with bc?

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39

9

It looks like bc doesn't support float operations, when I do echo 1/8 | bc it get me a zero.

I checked bc (1), but it doesn't even mention float, so I wonder if it's supported?

bc

share|improve this question

asked Mar 4 '13 at 2:07

daisydaisy

30.5k5353 gold badges182182 silver badges312312 bronze badges

• 
  
  
  

  
  8
  

  
  
  
  
  
  

  
  
  echo "scale=4; 1/8" | bc
  
  – LiuYan 刘研
  Mar 4 '13 at 2:20
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This question and in particular the accepted answer might be interesting to you.
  
  – Emanuel Berg
  Mar 6 '13 at 1:21
  

  
  
  
  

add a comment | 

39

9

It looks like bc doesn't support float operations, when I do echo 1/8 | bc it get me a zero.

I checked bc (1), but it doesn't even mention float, so I wonder if it's supported?

bc

share|improve this question

asked Mar 4 '13 at 2:07

daisydaisy

30.5k5353 gold badges182182 silver badges312312 bronze badges

• 
  
  
  

  
  8
  

  
  
  
  
  
  

  
  
  echo "scale=4; 1/8" | bc
  
  – LiuYan 刘研
  Mar 4 '13 at 2:20
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This question and in particular the accepted answer might be interesting to you.
  
  – Emanuel Berg
  Mar 6 '13 at 1:21
  

  
  
  
  

add a comment | 

It looks like bc doesn't support float operations, when I do echo 1/8 | bc it get me a zero.

I checked bc (1), but it doesn't even mention float, so I wonder if it's supported?

bc

share|improve this question

asked Mar 4 '13 at 2:07

daisydaisy

30.5k5353 gold badges182182 silver badges312312 bronze badges

share|improve this question

asked Mar 4 '13 at 2:07

daisydaisy

30.5k5353 gold badges182182 silver badges312312 bronze badges

share|improve this question

asked Mar 4 '13 at 2:07

daisydaisy

30.5k5353 gold badges182182 silver badges312312 bronze badges

asked Mar 4 '13 at 2:07

daisydaisy

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asked Mar 4 '13 at 2:07

daisydaisy

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3 Answers
3

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55

bc doesn't do floating point but it does do fixed precision decimal numbers. The -l flag Hauke mentions loads a math library for eg. trig functions but it also means

[...] the default scale is 20

scale is one of a number of "special variables" mentioned in the man page. You can set it:

scale=4

Anytime you want (whether -l was used or not). It refers to the number of significant digits used in a decimal. In other words, subsequent solutions will be rounded to that number of digits after the decimal scale (== fixed precision).

The default scale sans -l is 0, meaning rounded to whole numbers.

share|improve this answer

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

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add a comment | 

25

man page says:

If bc is invoked with the -l option, a math library is preloaded [...]

The comprehensibility of that could be improved, indeed...

share|improve this answer

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

• 
  
  
  

  
  14
  

  
  
  
  
  
  

  
  
  Report it upstream as a bug...
  
  – vonbrand
  Mar 4 '13 at 3:18
  

  
  
  
  

add a comment | 

0

1) Numbers in bc have a scale. The scale of a number should not be confused with the scale factor. The same world 'scale' is used as a function to query the scale of a number or as a parameter to set the scale factor.

echo "scale=scale(1.1);11/10" | bc will return 1.1

2) The scale factor determines how many digits are kept to the right of the decimal point when doing operations. If s is the current scale factor, sa is the scale of the first operand a, sb is the scale of the second operand b, results are truncated as follow :

    scale of result

a+b     max(sa,sb)

a-b     max(sa,sb)

a*b     min(sa+sb , max(s,sa,sb))

a/b     s

a%b     so that a = b*quotient + remainder; remainder has sign of a

a^b     min(sa×|b|, max(s,sa)); b must be integer

sqrt(a) max(s,sa)

3) At the origin bc was a preprocessor of dc. Now, on many systems, bc is a standalone program.

Source : [https://plan9.io/magic/man2html/1/dc]

share|improve this answer

answered 2 days ago

cd9cd9

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55

bc doesn't do floating point but it does do fixed precision decimal numbers. The -l flag Hauke mentions loads a math library for eg. trig functions but it also means

[...] the default scale is 20

scale is one of a number of "special variables" mentioned in the man page. You can set it:

scale=4

Anytime you want (whether -l was used or not). It refers to the number of significant digits used in a decimal. In other words, subsequent solutions will be rounded to that number of digits after the decimal scale (== fixed precision).

The default scale sans -l is 0, meaning rounded to whole numbers.

share|improve this answer

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

add a comment | 

55

bc doesn't do floating point but it does do fixed precision decimal numbers. The -l flag Hauke mentions loads a math library for eg. trig functions but it also means

[...] the default scale is 20

scale is one of a number of "special variables" mentioned in the man page. You can set it:

scale=4

Anytime you want (whether -l was used or not). It refers to the number of significant digits used in a decimal. In other words, subsequent solutions will be rounded to that number of digits after the decimal scale (== fixed precision).

The default scale sans -l is 0, meaning rounded to whole numbers.

share|improve this answer

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

add a comment | 

bc doesn't do floating point but it does do fixed precision decimal numbers. The -l flag Hauke mentions loads a math library for eg. trig functions but it also means

[...] the default scale is 20

scale is one of a number of "special variables" mentioned in the man page. You can set it:

scale=4

Anytime you want (whether -l was used or not). It refers to the number of significant digits used in a decimal. In other words, subsequent solutions will be rounded to that number of digits after the decimal scale (== fixed precision).

The default scale sans -l is 0, meaning rounded to whole numbers.

share|improve this answer

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

scale=4

share|improve this answer

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

answered Mar 4 '13 at 2:25

goldilocksgoldilocks

65.5k1818 gold badges165165 silver badges218218 bronze badges

25

man page says:

If bc is invoked with the -l option, a math library is preloaded [...]

The comprehensibility of that could be improved, indeed...

share|improve this answer

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

• 
  
  
  

  
  14
  

  
  
  
  
  
  

  
  
  Report it upstream as a bug...
  
  – vonbrand
  Mar 4 '13 at 3:18
  

  
  
  
  

add a comment | 

25

man page says:

If bc is invoked with the -l option, a math library is preloaded [...]

The comprehensibility of that could be improved, indeed...

share|improve this answer

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

• 
  
  
  

  
  14
  

  
  
  
  
  
  

  
  
  Report it upstream as a bug...
  
  – vonbrand
  Mar 4 '13 at 3:18
  

  
  
  
  

add a comment | 

man page says:

If bc is invoked with the -l option, a math library is preloaded [...]

The comprehensibility of that could be improved, indeed...

share|improve this answer

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

share|improve this answer

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

59.8k1212 gold badges9393 silver badges140140 bronze badges

answered Mar 4 '13 at 2:17

Hauke LagingHauke Laging

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0

1) Numbers in bc have a scale. The scale of a number should not be confused with the scale factor. The same world 'scale' is used as a function to query the scale of a number or as a parameter to set the scale factor.

echo "scale=scale(1.1);11/10" | bc will return 1.1

2) The scale factor determines how many digits are kept to the right of the decimal point when doing operations. If s is the current scale factor, sa is the scale of the first operand a, sb is the scale of the second operand b, results are truncated as follow :

    scale of result

a+b     max(sa,sb)

a-b     max(sa,sb)

a*b     min(sa+sb , max(s,sa,sb))

a/b     s

a%b     so that a = b*quotient + remainder; remainder has sign of a

a^b     min(sa×|b|, max(s,sa)); b must be integer

sqrt(a) max(s,sa)

3) At the origin bc was a preprocessor of dc. Now, on many systems, bc is a standalone program.

Source : [https://plan9.io/magic/man2html/1/dc]

share|improve this answer

answered 2 days ago

cd9cd9

111 bronze badge

New contributor

cd9 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

0

1) Numbers in bc have a scale. The scale of a number should not be confused with the scale factor. The same world 'scale' is used as a function to query the scale of a number or as a parameter to set the scale factor.

echo "scale=scale(1.1);11/10" | bc will return 1.1

2) The scale factor determines how many digits are kept to the right of the decimal point when doing operations. If s is the current scale factor, sa is the scale of the first operand a, sb is the scale of the second operand b, results are truncated as follow :

    scale of result

a+b     max(sa,sb)

a-b     max(sa,sb)

a*b     min(sa+sb , max(s,sa,sb))

a/b     s

a%b     so that a = b*quotient + remainder; remainder has sign of a

a^b     min(sa×|b|, max(s,sa)); b must be integer

sqrt(a) max(s,sa)

3) At the origin bc was a preprocessor of dc. Now, on many systems, bc is a standalone program.

Source : [https://plan9.io/magic/man2html/1/dc]

share|improve this answer

answered 2 days ago

cd9cd9

111 bronze badge

New contributor

cd9 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

1) Numbers in bc have a scale. The scale of a number should not be confused with the scale factor. The same world 'scale' is used as a function to query the scale of a number or as a parameter to set the scale factor.

echo "scale=scale(1.1);11/10" | bc will return 1.1

2) The scale factor determines how many digits are kept to the right of the decimal point when doing operations. If s is the current scale factor, sa is the scale of the first operand a, sb is the scale of the second operand b, results are truncated as follow :

    scale of result

a+b     max(sa,sb)

a-b     max(sa,sb)

a*b     min(sa+sb , max(s,sa,sb))

a/b     s

a%b     so that a = b*quotient + remainder; remainder has sign of a

a^b     min(sa×|b|, max(s,sa)); b must be integer

sqrt(a) max(s,sa)

3) At the origin bc was a preprocessor of dc. Now, on many systems, bc is a standalone program.

Source : [https://plan9.io/magic/man2html/1/dc]

share|improve this answer

answered 2 days ago

cd9cd9

111 bronze badge

New contributor

cd9 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

echo "scale=scale(1.1);11/10" | bc will return 1.1

    scale of result

a+b     max(sa,sb)

a-b     max(sa,sb)

a*b     min(sa+sb , max(s,sa,sb))

a/b     s

a%b     so that a = b*quotient + remainder; remainder has sign of a

a^b     min(sa×|b|, max(s,sa)); b must be integer

sqrt(a) max(s,sa)

share|improve this answer

answered 2 days ago

cd9cd9

111 bronze badge

New contributor

cd9 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

answered 2 days ago

cd9cd9

111 bronze badge

New contributor

cd9 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

answered 2 days ago

cd9cd9

111 bronze badge