Real*8 Xold, Xnew, EPSILON

CSE 1540.03 program Week9v2 Week 10.1 March 17, 2014 implicit none real*8 xold, xnew, EPSILON real*8 f, fprime parameter (EPSILON = 1.d-8) program Week9v1 implicit none read*, xold do real*8 xold, xnew, EPSILON xnew = xold - f(xold)/fprime(xold) parameter (EPSILON = 1.d-8) if (dabs(xnew-xold) .lt. EPSILON) exit xold = xnew read*, xold end do do print*, "x* = ", xnew xnew = xold - (xold*xold-1)/(2.d0*xold) if (dabs(xnew-xold) .lt. EPSILON) exit end xold = xnew end do real*8 function f (x) print*, "x* = ", xnew real*8 x f = x*x - 1 end return end

real*8 function fprime (x) real*8 x fprime = 2*x return end

CSE 1540 Week 10.1 – March 17, 2014 page 1 of 3 program Week9v3 program Week9v4 implicit none implicit none real*8 b, c, EPS real*8 x, EPSILON real*8 f integer status external f real*8 f, fprime integer status external f, fprime parameter (EPS = 1.d-8) parameter (EPSILON = 1.d-8) print*, "Enter (b,c) interval: " read*, x read*, b, c call dmyZero(f,fprime,x,EPSILON,status) call dfzero(f,b,c,b,EPS,EPS,status) print*, "x* = ", x print*, "x* = (", b, ",", c, ")" print*, "Status = ", status end end subroutine dmyZero (f,fprime,x,eps,iflag) real*8 function f (x) real*8 f, fprime, x, eps, xnew, xold real*8 x external f, fprime f = x*x - 1 integer iflag, i return end xold = x do i=1,100 xnew = xold - f(xold)/fprime(xold) if (dabs(xnew-xold) .lt. eps) then iflag = 1 x = xnew return end if xold = xnew end do iflag = 2 return end

real*8 function f (x) real*8 x f = x*x - 1 return end

real*8 function fprime (x) real*8 x fprime = 2*x return

CSE 1540 Week 10.1 – March 17, 2014 page 2 of 3 end program Week9v5 program Mortgage implicit none implicit none real*8 b, c, EPS integer n real*8 dbesj1 real*8 rold, rnew, A, P, EPSILON external dbesj1 real*8 f, fprime integer status parameter (EPSILON = 1.d-8) parameter (EPS = 1.d-8) read*, n, A, P print*, "Enter (b,c) interval: " read*, rold read*, b, c do call dfzero(dbesj1,b,c,b,EPS,EPS,status) rnew = rold - f(rold,n,A,P)/fprime(rold,n,A,P) print*, "x* = (", b, ",", c, ")" if (dabs(rnew-rold) .lt. EPSILON) exit print*, "Status = ", status rold = rnew end do end print*, "Interest Rate = ", rnew * 12

real*8 function f (r,n,A,P) real*8 r, A, P integer n f = 1.d0 – (1.d0 + r)**(-n) – A*r/P return end

real*8 function fprime (r,n,A,P) real*8 r, A, P integer n fprime = n*(1.d0 + r)**(-n-1) – A/P return end

CSE 1540 Week 10.1 – March 17, 2014 page 3 of 3