1 files changed, 55 insertions, 0 deletions
diff --git a/examples/shellmath/slower_e_demo.sh b/examples/shellmath/slower_e_demo.sh
new file mode 100644
index 0000000..d8fc931
--- /dev/null
+++ b/examples/shellmath/slower_e_demo.sh
@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+###############################################################################
+# This script illustrates the use of the shellmath APIs to perform
+# decimal calculations. Here we approximate the mathematical constant 'e'
+# using its Maclaurin polynomials (i.e. its Taylor polynomials centered at 0).
+###############################################################################
+
+source shellmath.sh
+
+# Setting the '-t' flag will cause the script to time the algorithm
+if [[ "$1" == '-t' ]]; then
+    do_timing=${__shellmath_true}
+    shift
+fi
+
+if [[ $# -ne 1 ]]; then
+    echo "USAGE: ${BASH_SOURCE##*/}  [-t]  *N*"
+    echo "       Approximates 'e' using the N-th order Maclaurin polynomial"
+    echo "       (i.e. the Taylor polynomial centered at 0)."
+    echo "       Specify the '-t' flag to time the main algorithm."
+    exit 0
+elif [[ ! "$1" =~ ^[0-9]+$ ]]; then
+    echo "Illegal argument. Whole numbers only, please."
+    exit 1
+fi
+
+
+function run_algorithm()
+{
+    # Initialize
+    n=0;  N=$1;  zero_factorial=1
+
+    # Initialize e to the zeroth-order term
+    term=$(_shellmath_divide  1  $zero_factorial)
+    e=$term
+
+    # Compute successive terms T(n) := T(n-1)/n and accumulate into e
+    for ((n=1; n<=N; n++)); do
+        term=$(_shellmath_divide  "$term"  "$n")
+        e=$(_shellmath_add  "$e"  "$term")
+    done
+
+    echo "e = $e"
+}
+
+
+if (( do_timing == __shellmath_true )); then
+    time run_algorithm "$1"
+else
+    run_algorithm "$1"
+fi
+
+exit 0
+