cleanup subroutine example; add preallocated pivot

Author: perazz

example/linalg/example_solve3.f90

@@ -1,9 +1,10 @@
 program example_solve3
-  use stdlib_linalg_constants, only: sp
+  use stdlib_linalg_constants, only: sp,ilp
   use stdlib_linalg, only: solve_lu, linalg_state_type 
   implicit none
 
   integer(ilp) :: test
+  integer(ilp), allocatable :: pivot(:)
   complex(sp), allocatable :: A(:,:),b(:),x(:)
 
   ! Solve a system of 3 complex linear equations: 
@@ -15,15 +16,16 @@ program example_solve3
   A = transpose(reshape([(2.0, 0.0),(0.0, 1.0),(2.0,0.0), &
                          (0.0,-1.0),(4.0,-3.0),(6.0,0.0), &
                          (4.0, 0.0),(3.0, 0.0),(1.0,0.0)] , [3,3])) 
-  b = [(5.0,-1.0),(0.0,1.0),(1.0,0.0)]
 
   ! Pre-allocate x
-  allocate(x,source=b)
+  allocate(b(size(A,2)),pivot(size(A,2)))
+  allocate(x,mold=b)
 
   ! Call system many times avoiding reallocation 
   do test=1,100
-     call solve_lu(A,b,x)
-     print "(i2,'-th solution: ',*(1x,f12.6))", test,x
+     b = test*[(5.0,-1.0),(0.0,1.0),(1.0,0.0)]
+     call solve_lu(A,b,x,pivot)
+     print "(i3,'-th solution: ',*(1x,f12.6))", test,x
   end do
 
 end program example_solve3