'                               ***home work 2***
'                               ***Reading Data***
CLS
PRINT "A * X = B"
INPUT "Enter DEGREE of system of equations:", n
FOR i = 1 TO n
 FOR j = 1 TO n
  PRINT "Enter A("; i; ","; j;
 
  INPUT "):", a(i, j)
 NEXT
 PRINT
NEXT

PRINT
FOR i = 1 TO n
 PRINT "Enter B("; i;
 INPUT "):", a(i, n + 1)
NEXT

'                               ***Gause Elemination***
FOR f = 1 TO n
 nc = 1
 m = -1000000
 FOR i = f TO n
  FOR j = f TO n
   IF a(i, j) > m THEN nc = j: m = a(i, j)
  NEXT
 NEXT
 nr = 1
 m = -1000000
 FOR i = f TO n
  FOR j = f TO n
   IF a(i, j) > m THEN nr = i: m = a(i, j)
  NEXT
 NEXT

 FOR t = 1 TO n
  SWAP a(t, nc), a(t, f)
 NEXT
 FOR t = 1 TO n + 1
  SWAP a(nr, t), a(f, t)
 NEXT

 FOR j = f TO n
  m = a(j + 1, f) / a(f, f)
  FOR k = f TO n + 1
   a(j + 1, k) = a(j + 1, k) - a(f, k) * m
  NEXT k
 NEXT j
NEXT f
'                               ***Computing X***

FOR i = n TO 1 STEP -1
 s = 0
 FOR j = i + 1 TO n
  s = s + a(i, j) * x(j)
 NEXT
 x(i) = (a(i, n + 1) - s) / a(i, i)
NEXT

PRINT
'                               ***Output***
'FOR i = 1 TO n
' FOR j = 1 TO n + 1
'  PRINT a(i, j); "  ";
' NEXT
' PRINT
'NEXT

FOR i = 1 TO n
 PRINT "X"; i; "="; x(i)
NEXT