如何在Bash中比较两个浮点数？

#1 楼

if (( $(echo "$num1 > $num2" |bc -l) )); then
  …
fi

#2 楼

$ num1=3.17648E-22
$ num2=1.5
$ echo $num1'>'$num2 | bc -l
0
$ echo $num2'>'$num1 | bc -l
1

#3 楼

numCompare() {
   awk -v n1="" -v n2="" 'BEGIN {printf "%s " (n1<n2?"<":">=") " %s\n", n1, n2}'
}

numCompare 5.65 3.14e-22
5.65 >= 3.14e-22

numCompare 5.65e-23 3.14e-22
5.65e-23 < 3.14e-22

numCompare 3.145678 3.145679
3.145678 < 3.145679

#4 楼

if [ ${FOO%.*} -eq ${BAR%.*} ] && [ ${FOO#*.} \> ${BAR#*.} ] || [ ${FOO%.*} -gt ${BAR%.*} ]; then
  echo "${FOO} > ${BAR}";
else
  echo "${FOO} <= ${BAR}";
fi

#5 楼

if awk 'BEGIN {exit !('$d1' >= '$d2')}'; then
    echo "yes"
else 
    echo "no"
fi

#6 楼

$ awk 'BEGIN { print (2.20 >= 2.6) ? "YES" : "NO" }'
NO

$ awk 'BEGIN { print (2.2 >= 2.6) ? "YES" : "NO" }'
NO

$ awk 'BEGIN { print (2.60 == 2.6) ? "YES" : "NO" }'
YES

# get version of GNU tool
toolversion() {
    local prog="" operator="" value="" version

    version=$($prog --version | awk '{print $NF; exit}')

    awk -vv1="$version" -vv2="$value" 'BEGIN {
        split(v1, a, /\./); split(v2, b, /\./);
        if (a[1] == b[1]) {
            exit (a[2] '$operator' b[2]) ? 0 : 1
        }
        else {
            exit (a[1] '$operator' b[1]) ? 0 : 1
        }
    }'
}

if toolversion grep '>=' 2.6; then
   # do something awesome
fi

#7 楼

if [[ $((10#${num1/.})) < $((10#${num2/.})) ]]; then
    ...

#8 楼

is_first_floating_number_bigger 1.5 1.2
result="${__FUNCTION_RETURN}"

is_first_floating_number_bigger () {
    number1=""
    number2=""

    [ ${number1%.*} -eq ${number2%.*} ] && [ ${number1#*.} \> ${number2#*.} ] || [ ${number1%.*} -gt ${number2%.*} ];
    result=$?
    if [ "$result" -eq 0 ]; then result=1; else result=0; fi

    __FUNCTION_RETURN="${result}"
}

is_first_floating_number_bigger () {
    number1=""
    number2=""

    echo "... is_first_floating_number_bigger: comparing ${number1} with ${number2} (to check if the first one is bigger)"

    [ ${number1%.*} -eq ${number2%.*} ] && [ ${number1#*.} \> ${number2#*.} ] || [ ${number1%.*} -gt ${number2%.*} ];
    result=$?
    if [ "$result" -eq 0 ]; then result=1; else result=0; fi

    echo "... is_first_floating_number_bigger: result is: ${result}"

    if [ "$result" -eq 0 ]; then
        echo "... is_first_floating_number_bigger: ${number1} is not bigger than ${number2}"
    else
        echo "... is_first_floating_number_bigger: ${number1} is bigger than ${number2}"
    fi

    __FUNCTION_RETURN="${result}"
}

#9 楼

#!/bin/bash

export num1=(3.17648*e-22)
export num2=1.5

st=$((`echo "$num1 < $num2"| bc`))
if [ $st -eq 1 ]
  then
    echo -e "$num1 < $num2"
  else
    echo -e "$num1 >= $num2"
fi

#10 楼

$ cat tst.sh
#!/bin/bash

num1=3.17648e-22
num2=1.5

awk -v num1="$num1" -v num2="$num2" '
BEGIN {
    print "num1", (num1 < num2 ? "<" : ">="), "num2"
}
'

$ ./tst.sh
num1 < num2

$ cat tst.sh
#!/bin/bash

read -p "Operator: " operator
read -p "First number: " ch1
read -p "Second number: " ch2

awk -v ch1="$ch1" -v ch2="$ch2" -v op="$operator" '
BEGIN {
    if ( ( op == "/" ) && ( ch2 == 0 ) ) {
        print "Nope..."
    }
    else {
        print ch1 '"$operator"' ch2
    }
}
'

$ ./tst.sh
Operator: /
First number: 4.5
Second number: 2
2.25

$ ./tst.sh
Operator: /
First number: 4.5
Second number: 0
Nope...

#11 楼

num1=3.17648E-22
num2=1.5
if python -c "exit(0 if $num1 < $num2 else 1)"; then
    echo "yes, $num1 < $num2"
else
    echo "no, $num1 >= $num2"
fi

#12 楼

 if (( $(bc -l <<< "${value1/e/E} < ${value2/e/E}") ))
then
    echo "$value1 is below $value2"
fi 
 

#13 楼

#!/bin/bash                                                                                         

min=1.4                                                                                             
current=`echo $(grails --version | head -n 2 | awk '{print $NF}' | cut -c 1-3)`                         

if [ 1 -eq `echo "${current} < ${min}" | bc` ]                                                          
then                                                                                                
    echo "yo, you have older version of grails."                                                   
else                                                                                                                                                                                                                       
    echo "Hurray, you have the latest version" 
fi

#14 楼

num1=0.555
num2=2.555


if [ `echo "$num1>$num2"|bc` -eq 1 ]; then
       echo "$num1 is greater then $num2"
else
       echo "$num2 is greater then $num1"
fi

#15 楼

#!/bin/ksh
X=0.2
Y=0.2
echo $X
echo $Y

if [[ $X -lt $Y ]]
then
     echo "X is less than Y"
elif [[ $X -gt $Y ]]
then
     echo "X is greater than Y"
elif [[ $X -eq $Y ]]
then
     echo "X is equal to Y"
fi

#16 楼

#!/usr/bin/bashj

#!java
static int doubleCompare(double a,double b) {return((a>b) ? 1 : (a<b) ? -1 : 0);}

#!bashj
num1=3.17648e-22
num2=1.5
comp=j.doubleCompare($num1,$num2)
if [ $comp == 0 ] ; then echo "Equal" ; fi
if [ $comp == 1 ] ; then echo "$num1 > $num2" ; fi
if [ $comp == -1 ] ; then echo "$num2 > $num1" ; fi

#17 楼

VAL_TO_CHECK="1.00001"
if [ $(awk '{printf( >= ) ? 1 : 0}' <<<" $VAL_TO_CHECK 1 ") -eq 1 ] ; then
    echo "$VAL_TO_CHECK >= 1"
else
    echo "$VAL_TO_CHECK < 1"
fi