1 files changed, 46 insertions, 0 deletions
diff --git a/ext/bigdecimal/sample/linear.rb b/ext/bigdecimal/sample/linear.rb
new file mode 100644
index 0000000000..f93404fb6f
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+++ b/ext/bigdecimal/sample/linear.rb
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+#!/usr/local/bin/ruby
+
+#
+# linear.rb
+#
+# Solves linear equation system(A*x = b) by LU decomposition method.
+#  where  A is a coefficient matrix,x is an answer vector,b is a constant vector.
+#
+require "bigdecimal"
+require "ludcmp"
+
+include LUSolve
+
+def rd_order
+   printf("Number of equations ?")
+   n = gets().chomp.to_i
+end
+
+zero = BigDecimal::new("0.0")
+one  = BigDecimal::new("1.0")
+
+while (n=rd_order())>0
+  a = []
+  as= []
+  b = []
+  printf("\nEnter coefficient matrix element A[i,j]\n");
+  for i in 0...n do
+    for j in 0...n do
+      printf("A[%d,%d]? ",i,j); s = gets
+      a <<=BigDecimal::new(s);
+      as<<=BigDecimal::new(s);
+    end
+    printf("Contatant vector element b[%d] ? ",i);b<<=BigDecimal::new(gets);
+  end
+  printf "ANS="
+  x = lusolve(a,b,ludecomp(a,n,zero,one),zero)
+  p x
+  printf "A*x-b\n"
+  for i in 0...n do
+    s = zero
+    for j in 0...n do
+       s = s + as[i*n+j]*x[j]
+    end
+    p s-b[i]
+  end
+end