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fixed bug in diff module with the sign function. #15

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fixed bug in diff module with the sign function. #15

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6 changes: 3 additions & 3 deletions src/cache_module.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ subroutine initialize_cache(me,isize,n,m,chunk_size)

class(function_cache),intent(inout) :: me
integer,intent(in) :: isize !! the size of the hash table
integer,intent(in) :: n !! number of independant variables (x)
integer,intent(in) :: n !! number of independent variables (x)
integer,intent(in) :: m !! number of functions (f)
integer,intent(in),optional :: chunk_size !! chunk size to speed up reallocation
!! of arrays. A good value is a guess for
Expand Down Expand Up @@ -127,7 +127,7 @@ subroutine get_from_cache(me,x,ifs,i,f,xfound,ffound)
implicit none

class(function_cache),intent(inout) :: me
real(wp),dimension(:),intent(in) :: x !! independant variable vector
real(wp),dimension(:),intent(in) :: x !! independent variable vector
integer,dimension(:),intent(in) :: ifs !! elements of `f` needed
integer,intent(out) :: i !! index in the hash table
real(wp),dimension(:),intent(out) :: f !! `f(x)` from the cache (if it was found)
Expand Down Expand Up @@ -178,7 +178,7 @@ subroutine put_in_cache(me,i,x,f,ifs)

class(function_cache),intent(inout) :: me
integer,intent(in) :: i !! index in the hash table
real(wp),dimension(:),intent(in) :: x !! independant variable vector (dimension `n`)
real(wp),dimension(:),intent(in) :: x !! independent variable vector (dimension `n`)
real(wp),dimension(:),intent(in) :: f !! function vector `f(x)` (dimension `m`)
integer,dimension(:),intent(in) :: ifs !! elements of `f` to add (should all be `>0, <=m`)

Expand Down
10 changes: 5 additions & 5 deletions src/diff_module.f90
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Expand Up @@ -7,7 +7,7 @@
!## Authors
! * J. Oliver, "An algorithm for numerical differentiation of a function
! of one real variable", Journal of Computational and Applied Mathematics
! 6 (2) (1980) 145–160. [Algol 60 source in original paper]
! 6 (2) (1980) 145-160. [Algol 60 source in original paper]
! * David Kahaner, Fortran 77 code from
! [NIST](ftp://math.nist.gov/pub/repository/diff/src/DIFF)
! * Jacob Williams : 2/17/2013 : Converted to modern Fortran.
Expand Down Expand Up @@ -834,7 +834,7 @@ subroutine faccur(me,h0,h1,facc,x0,twoinf,f0,f1,ifail)
end if
end if
if (abs(h1) >= 32.0_wp*twoinf) h1 = h1/8.0_wp
if (16.0_wp*abs(h1) > abs(h0)) h1 = sign(h1,1.0_wp)*abs(h0)/16.0_wp
if (16.0_wp*abs(h1) > abs(h0)) h1 = sign(1.0_wp,h1)*abs(h0)/16.0_wp
f001 = me%f(x0+h0-h1)
if (me%stop) then
ifail = -1
Expand All @@ -854,7 +854,7 @@ subroutine faccur(me,h0,h1,facc,x0,twoinf,f0,f1,ifail)
end do
h1 = 8.0_wp*h1
else
h1 = sign(h1,1.0_wp)*abs(h0)/16.0_wp
h1 = sign(1.0_wp,h1)*abs(h0)/16.0_wp
end if
else
if (256.0_wp*twoinf <= abs(h0)) then
Expand All @@ -868,9 +868,9 @@ subroutine faccur(me,h0,h1,facc,x0,twoinf,f0,f1,ifail)
h1 = h1/2.0_wp
end do
h1 = 8.0_wp*h1
if (16.0_wp*abs(h1) > abs(h0)) h1 = sign(h1,1.0_wp)*abs(h0)/16.0_wp
if (16.0_wp*abs(h1) > abs(h0)) h1 = sign(1.0_wp,h1)*abs(h0)/16.0_wp
else
h1 = sign(h1,1.0_wp)*abs(h0)/16.0_wp
h1 = sign(1.0_wp,h1)*abs(h0)/16.0_wp
end if
end if
else
Expand Down
2 changes: 1 addition & 1 deletion src/utilities_module.f90
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Expand Up @@ -179,7 +179,7 @@ function unique_real(vec,chunk_size) result(ivec_unique)

implicit none

real(wp),dimension(:),intent(in) :: vec !! a vector of integers
real(wp),dimension(:),intent(in) :: vec !! a vector of reals
integer,intent(in) :: chunk_size !! chunk size for adding to arrays
real(wp),dimension(:),allocatable :: ivec_unique !! unique elements of `ivec`

Expand Down
2 changes: 1 addition & 1 deletion tests/test2.f90
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Expand Up @@ -74,7 +74,7 @@ program test2
font_size = 30, &
xlabel = 'Finite Difference Perturbation Step Size $h$',&
ylabel = 'Finite Difference Derivative Error',&
title = 'Derivative of $x + \sin(x)$ at $x=1$ '//real_kind_str,&
title = 'Derivative of $x + \\sin(x)$ at $x=1$ '//real_kind_str,&
legend = .true., &
legend_fontsize = 10,&
usetex = .true.)
Expand Down
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