|
Size: 2210
Comment: spam
|
Size: 322
Comment: 3.33333333333333
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 1: | Line 1: |
| <<Anchor(faq22)>> == How can I calculate with floating point numbers instead of just integers? == [[BASH]] does not have built-in floating point [[ArithmeticExpression|arithmetic]]: {{{ $ echo $((10/3)) 3 }}} Bash cannot do ''anything'' with floating point numbers, ''including'' compare them to each other(*). Instead, an external program must be used, e.g. {{{bc}}}, {{{awk}}} or {{{dc}}}: {{{ $ echo "scale=3; 10/3" | bc 3.333 }}} The "scale=3" command notifies {{{bc}}} that three digits of precision after the decimal point are required. If you are trying to compare floating point numbers, be aware that a simple ''x < y'' is not supported by all versions of {{{bc}}}. {{{ # This would work with some versions, but not HP-UX 10.20. # The here string feature, inherited from rc->zsh->ksh93 was # introduced in bash 2.05b-alpha1 imadev:~$ bc <<< '1 < 2' syntax error on line 1, }}} Alternatively, you could use this: {{{ # Bash if [[ $(bc <<< "1.4 - 2.5") = -* ]]; then echo "1.4 is less than 2.5." fi }}} This example subtracts 2.5 from 1.4, and checks the sign of the result. If it is negative, the first number is less than the second. Portable version: {{{ # Bourne case "`echo "1.4 - 2.5" | bc`" in -*) echo "1.4 is less than 2.5";; esac }}} [[AWK]] can be used for calculations, too: {{{ $ awk 'BEGIN {printf "%.3f\n", 10 / 3}' 3.333 }}} There is a subtle but important difference between the {{{bc}}} and the {{{awk}}} solution here: {{{bc}}} reads commands and expressions from ''standard input''. {{{awk}}} on the other hand evaluates the expression as ''part of the program''. Expressions on standard input are ''not'' evaluated, i.e. {{{echo 10/3 | awk '{print $0}'}}} will print {{{10/3}}} instead of the evaluated result of the expression. Newer versions of zsh and the KornShell have built-in floating point arithmetic, together with mathematical functions like {{{sin()}}} or {{{cos()}}} . (*)Actually, I lied. It can print them, using {{{printf}}} and one of the {{{%e}}} or {{{%f}}} or {{{%g}}} format strings. But that's all. |
It has been two years of agonising pain and incredible hard work but YOU'VE DONE IT! We are all very proud of you and the way that you have used your terrible accident to help others who have found themselves amputees, http://roni60.justfree.com/beaches-65/easy-ginger-bread-recipe.html easy ginger bread recipe, 9450, |
It has been two years of agonising pain and incredible hard work but YOU'VE DONE IT! We are all very proud of you and the way that you have used your terrible accident to help others who have found themselves amputees, http://roni60.justfree.com/beaches-65/easy-ginger-bread-recipe.html easy ginger bread recipe, 9450,