anchor.diff:        mbad = 0                     !No errors yet.
   C..........SET RIGHT-HAND AND SOLUTION VECTORS TO INITIAL VALUES.
         DO i = 1,isize
  -        x(i) = b(i)                !Right-hand vector.
  +        x(i) = b_(i)                !Right-hand vector.
           y(i) = 0.                  !Solution vector.
         END DO
   C..........SAVE MATRIX.
  
positive.code:         part1 = 1./(1.+ex(+.511*x/t9mev))
          part2 = 1./(1.+ex(-(x+2.531)*(.511/tnmev)-xi(1)))
  C       func2 = cnorm*(x+b*.511)*(x+2.531)**2*(x**2-1)**.5*part1*part2
        IF (x.gt.(2.531) THEN
          func2 = cnorm*(x-b*.511)*(x+2.531)**2*(x**2-1)**.5*part1*part2
        ELSE
          func2 = cnorm*(x+b*.511)*(x+2.531)**2*(x**2-1)**.5*part1*part2
        END IF
        END IF
        RETURN
        end
  
negative.code: 
  C----------MATRIX COEFFICIENTS FOR LINEAR EQUATION.
        DOUBLE PRECISION a(nnuc,nnuc)!Coefficient array.
        REAL    b_(nnuc)              !Right-hand vector w/o manipulation.
        REAL    y(nnuc)              !Solution vector.
  
  C----------COUNTERS AND FLAGS.
  