Based on the calc function defined in BASH via AWK, we can perform floating point computation in BASH.
The $RANDOM variable gives a psuedo random integer that is within the range of [0, 32767] aka 16-bit. Then, we can generate a random point (X, Y) and compute the distance to the origin (0, 0). Count the number of points that fall inside the circle and the result will be the ratio multiplied by four.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | #!/bin/bash function calc() { awk "BEGIN { print $*; }" } function pi() { local n=$1 local total=0 local inside=0 local RAND_MAX=32767 local i=0 while [[ $i -lt $n ]]; do local x=$RANDOM local y=$RANDOM local xxyy=$(calc "(($x/$RAND_MAX)**2+($y/$RAND_MAX)**2)<=1") if [[ $xxyy -eq 1 ]]; then inside=$((inside+1)) fi total=$((total+1)) i=$((i+1)) done calc $inside*4/$total } if [[ -z "$1" ]]; then pi 5000 else pi $1 fi |
#!/bin/bash
function calc() {
awk "BEGIN { print $*; }"
}
function pi() {
local n=$1
local total=0
local inside=0
local RAND_MAX=32767
local i=0
while [[ $i -lt $n ]]; do
local x=$RANDOM
local y=$RANDOM
local xxyy=$(calc "(($x/$RAND_MAX)**2+($y/$RAND_MAX)**2)<=1")
if [[ $xxyy -eq 1 ]]; then
inside=$((inside+1))
fi
total=$((total+1))
i=$((i+1))
done
calc $inside*4/$total
}
if [[ -z "$1" ]]; then
pi 5000
else
pi $1
fiIf you don't specify the parameter (iterations of Monte carlo) it is default to 5000.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | $ ./pi.sh 11 3.1344 $ ./pi.sh 11 3.63636 $ ./pi.sh 11 2.90909 $ ./pi.sh 100 2.92 $ ./pi.sh 100 3.48 $ ./pi.sh 3.1512 $ ./pi.sh 1000 3.084 $ ./pi.sh 10000 3.1412 |
$ ./pi.sh 11 3.1344 $ ./pi.sh 11 3.63636 $ ./pi.sh 11 2.90909 $ ./pi.sh 100 2.92 $ ./pi.sh 100 3.48 $ ./pi.sh 3.1512 $ ./pi.sh 1000 3.084 $ ./pi.sh 10000 3.1412
More iterations higher accuracy of the Estimation which means we will get a better approximation of the Math Constant PI value.
Monte Carlo Simulation Algorithms to compute the Pi based on Randomness:
- Teaching Kids Programming – Area and Circumferences of Circle and Monte Carlo Simulation Algorithm of PI
- Using Parallel For in Java to Compute PI using Monte Carlo Algorithm
- Monte Carlo solution for Mathematics × Programming Competition #7
- R Programming Tutorial – How to Compute PI using Monte Carlo in R?
- C++ Coding Exercise – Parallel For – Monte Carlo PI Calculation
- Area of the Shadow? – The Monte Carlo Solution in VBScript
- VBScript Coding Exercise – Compute PI using Monte Carlo Random Method
- Computing Approximate Value of PI using Monte Carlo in Python
- How does the 8-bit BASIC perform on Famicom Clone – Subor SB2000 – FBasic – Compute PI approximation using Monte-Carlo method
- GoLang: Compute the Math Pi Value via Monte Carlo Simulation
- BASH Script to Compute the Math.PI constant via Monte Carlo Simulation
--EOF (The Ultimate Computing & Technology Blog) --
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