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Calculation and numbers

Calculating with bc

Quotes

There are different double quotes. Beware the you use the right ones This does not work due to the wrong type of quotes

$ echo57/43.1234567| bc
(standard_in) 1: illegal character: \342
(standard_in) 1: illegal character: \200
(standard_in) 1: illegal character: \234
(standard_in) 1: illegal character: \342
(standard_in) 1: illegal character: \200
(standard_in) 1: illegal character: \235

The second quote double, one wrong

$ echo "57/43.1234567"| bc
(standard_in) 1: illegal character: \342
(standard_in) 1: illegal character: \200
(standard_in) 1: illegal character: \235

The second quote wrong

$ echo "57/43.1234567” | bc
>

An other example with wrong quotes

$ echoscale=2;57/43.1234567| bcscale=2
bash: 57/43.1234567”: No such file or directory

Single and double quotes can be used
With the right quotes

$ echo "57/43.1234567" | bc
1
$ echo '57/43.1234567' | bc
1

Floating point calculations

With echo

echo "scale=2;57/43.1234567" | bc		# 1.32
echo 'scale=2;57/43.1234567' | bc		# 1.32

scale only works with divide, not with multiplication

echo 'scale=2;57*43.1234567' | bc		# 2458.0370319	( should be 2458.04 )

This can be resolved, apart from the correct rounding, can be acieved by deviding the result by 1

echo 'scale=2;57*43.1234567/1' | bc		# 2458.03

Without echo

bc <<< 'scale=4;1216.00*31.1034768'		# 37821.8277888
bc <<< 'scale=4;1216.00*31.1034768/1'		# 37821.8277
bc <<< '365 * 24 * 60 * 60'			# 31536000
bc <<< $((4+5))*5                               # 45

Correct rounding with scale as a variable
It might be safe to give the initial variable scale a different name

scale=3;echo "scale=$scale;(((10^$scale)*160*24.90385449058/1)+0.5)/(10^$scale)" | bc	# 3984.617
scale=3;bc <<< "scale=$scale;(((10^$scale)*160*24.90385449058/1)+0.5)/(10^$scale)"	# 3984.617

Number ranges

echo $(seq 10)1 2 3 4 5 6 7 8 9 10

Pi

a(x)The arctangent of x, arctangent returns radians
pi=$(echo "scale=10; 4*a(1)" | bc --mathlib)
bc <<< 15*$pi
# Result: 47.1238897980

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calculating.txt · Last modified: 16-06-2021 00:25 by wim