#!/bin/bash

# gendata.sh

# numbers are too big for bash, use bc or awk

function usage {

echo "usage: gendata.sh -d dataset [-n count] [-h]"

echo "generates various datasets by name"

echo

echo "-d: dataset name"

echo "-c: number of values to generate"

echo "supported datasets"

echo "taocp_table_551_mmix, default count 1000"

echo "taocp_table_551_original, default count 1000"

}

# generates data of 1000 values used in table 1 from section 5.5 of the mmix supplement for taocp vol 3

# The case N = 1000 refers to the sequence K_1, K_2,..., K_1000 of 32-bit keys defined by

# X_0 = 0

# X_(n+1) = (6364136223846793005 * X_n + 9754186451795953191) mod 2^64

# K_n = floor(X_n/2^32)

# For the multiplier, see Section 3.3.4, page 108; 9754186451795953191 is some random increment value

function taocp_table_551_mmix {

local n=$1

bc <<EOF

# insure integer mod

scale = 0

two_32 = 2^32

two_64 = 2^64

x = 0

for(n = 0; n < $n; ++n) {

x = (6364136223846793005 * x + 9754186451795953191) % two_64

k = x / two_32

print k, "\n"

}

EOF

}

# generates data of 1000 values used in table 1 from section 5.5 of taocp vol 3

# data is generated by the formula:

# K_1001 = 0

# K_(n-1) = (3141592621 * K_n + 2113148651) mod 10^10, for n = 1001,...,2

# numbers are too big for bash, use bc or awk

function taocp_table_551_original {

local count=$1

bc <<EOF

# insure integer mod

scale = 0

ten_10 = 10^10

count = $count

k[count + 1] = 0

for(n = count + 1; n >= 2; --n) {

k[n - 1] = (3141592621 * k[n] + 2113148651) % ten_10

}

for(i = 1; i <= $count; ++i) {

print k[i], "\n"

}

EOF

}

# main

while getopts "d:h" opt; do

case $opt in

d) dataset=$OPTARG;;

n) n=$OPTARG;;

h) usage; exit 0;;

*) usage; exit 1

esac

done

shift $((OPTIND-1))

[[ -z $dataset ]] && usage && exit 1

case $dataset in

taocp_table_551_mmix)

taocp_table_551_mmix ${n:=1000}

;;

taocp_table_551_original)

taocp_table_551_original ${n:=1000}

esac