Initial data commit

Task/Matrix-multiplication/UNIX-Shell/matrix-multiplication.sh

@@ -0,0 +1,183 @@
+#!/bin/bash
+
+DELAY=0 # increase this if printing of matrices should be slower
+
+echo "This script takes two matrices, henceforth called A and B,
+and returns their product, AB.
+
+For the time being, matrices can have integer components only.
+
+"
+
+read -p "Number of rows    of matrix A:  " arows
+read -p "Number of columns of matrix A:  " acols
+brows="$acols"
+echo
+echo    "Number of rows    of matrix B:  "$brows
+read -p "Number of columns of matrix B:  " bcols
+
+crows="$arows"
+ccols="$bcols"
+echo
+
+echo "Number of rows    of matrix AB:  " $crows
+echo "Number of columns of matrix AB:  " $ccols
+echo
+echo
+
+matrixa=( )
+matrixb=( )
+
+# input matrix A
+
+maxlengtha=0
+for ((row=1; row<=arows; row++)); do
+    for ((col=1; col<=acols; col++)); do
+	checkentry="false"
+	while [ "$checkentry" != "true" ]; do
+	    read -p "Enter component A[$row, $col]:  " number
+	    index=$(((row-1)*acols+col))
+	    matrixa[$index]="$number"
+	    [ "${matrixa[$index]}" -eq "$number" ] && checkentry="true"
+	    echo
+	done
+	entry="${matrixa[$index]}"
+	[ "${#entry}" -gt "$maxlengtha" ] && maxlengtha="${#entry}"
+    done
+    echo
+done
+
+# print matrix A to guard against errors
+
+if [ "$maxlengtha" -le "5" ]; then
+    width=8
+else
+    width=$((maxlengtha + 3))
+fi
+
+echo "This is matrix A:
+
+"
+
+for ((row=1; row<=arows; row++)); do
+    for ((col=1; col<=acols; col++)); do
+
+	index=$(((row-1)*acols+col))
+	printf "%${width}d" "${matrixa[$index]}"
+	sleep "$DELAY"
+
+    done
+    echo; echo # printf %s "\n\n" does not work...
+done
+
+echo
+echo
+
+# input matrix B
+
+maxlengthb=0
+for ((row=1; row<=brows; row++)); do
+    for ((col=1; col<=bcols; col++)); do
+	checkentry="false"
+	while [ "$checkentry" != "true" ]; do
+	    read -p "Enter component B[$row, $col]:  " number
+	    index=$(((row-1)*bcols+col))
+	    matrixb[$index]="$number"
+	    [ "${matrixb[$index]}" -eq "$number" ] && checkentry="true"
+	    echo
+	done
+	entry="${matrixb[$index]}"
+	[ "${#entry}" -gt "$maxlengthb" ] && maxlengthb="${#entry}"
+    done
+    echo
+done
+
+# print matrix B to guard against errors
+
+if [ "$maxlengthb" -le "5" ]; then
+    width=8
+else
+    width=$((maxlengthb + 3))
+fi
+
+echo "This is matrix B:
+
+"
+
+for ((row=1; row<=brows; row++)); do
+    for ((col=1; col<=bcols; col++)); do
+
+	index=$(((row-1)*bcols+col))
+	printf "%${width}d" "${matrixb[$index]}"
+	sleep "$DELAY"
+
+    done
+    echo; echo # printf %s "\n\n" does not work...
+done
+
+read -p "Hit enter to continue"
+
+# calculate matrix C := AB
+
+maxlengthc=0
+time for ((row=1; row<=crows; row++)); do
+    for ((col=1; col<=ccols; col++)); do
+	
+	# calculate component C[$row, $col]
+
+	runningtotal=0
+	for ((j=1; j<=acols; j++)); do
+	    rowa="$row"
+	    cola="$j"
+	    indexa=$(((rowa-1)*acols+cola))
+	    rowb="$j"
+	    colb="$col"
+	    indexb=$(((rowb-1)*bcols+colb))
+	
+	    entry_from_A=${matrixa[$indexa]}
+	    entry_from_B=${matrixb[$indexb]}
+
+	    subtotal=$((entry_from_A * entry_from_B))
+	    ((runningtotal+=subtotal))
+	done
+	
+	number="$runningtotal"
+
+	# store component in the result array
+	index=$(((row-1)*ccols+col))
+	matrixc[$index]="$number"
+
+	entry="${matrixc[$index]}"
+	[ "${#entry}" -gt "$maxlengthc" ] && maxlengthc="${#entry}"
+    done
+done
+
+echo
+read -p "Hit enter to continue"
+echo
+
+# print the matrix C
+
+if [ "$maxlengthc" -le "5" ]; then
+    width=8
+else
+    width=$((maxlengthc + 3))
+fi
+
+echo "The product matrix is:
+
+"
+
+for ((row=1; row<=crows; row++)); do
+    for ((col=1; col<=ccols; col++)); do
+
+	index=$(((row-1)*ccols+col))
+	printf "%${width}d" "${matrixc[$index]}"
+	sleep "$DELAY"
+
+    done
+    echo; echo # printf %s "\n\n" does not work...
+done
+
+echo
+echo