Fix wsave in fftf/fftb`: intent(inout) -> intent(in).

Author: zoziha

doc/specs/fftpack.md

@@ -99,7 +99,7 @@ for j=1,...,n
 ```
 
 `wsave`: Shall be a `real` array.
-This argument is `intent(inout)`.  
+This argument is `intent(in)`.  
 A `real` work array which must be dimensioned at least `4n+15` in the program that calls `zfftf`. 
 The wsave array must be initialized by calling subroutine `zffti(n,wsave)` and a different `wsave` array must be used for each different value of `n`.  
 This initialization does not have to be repeated so long as `n` remains unchanged thus subsequent transforms can be obtained faster than the first. 
@@ -169,7 +169,7 @@ for j=1,...,n
 ```
 
 `wsave`: Shall be a `real` array.
-This argument is `intent(inout)`.  
+This argument is `intent(in)`.  
 A `real` work array which must be dimensioned at least `4n+15` in the program that calls `zfftf`. The `wsave` array must be initialized by calling subroutine `zffti(n,wsave)` and a different `wsave` array must be used for each different value of `n`. This initialization does not have to be repeated so long as `n` remains unchanged thus subsequent transforms can be obtained faster than the first. The same `wsave` array can be used by `zfftf` and `zfftb`.  
 Contains initialization calculations which must not be destroyed between calls of subroutine `zfftf` or `zfftb`.
 
@@ -385,7 +385,7 @@ if n is even
 ```
 
 `wsave`: Shall be a `real` array.
-This argument is `intent(inout)`.  
+This argument is `intent(in)`.  
 A `real` work array which must be dimensioned at least `4n+15` in the program that calls `dfftf`. 
 The wsave array must be initialized by calling subroutine `dffti(n,wsave)` and a different `wsave` array must be used for each different value of `n`.  
 This initialization does not have to be repeated so long as `n` remains unchanged thus subsequent transforms can be obtained faster than the first. 
@@ -464,7 +464,7 @@ for n odd and for i = 1,...,n
 ```
 
 `wsave`: Shall be a `real` array.
-This argument is `intent(inout)`.  
+This argument is `intent(in)`.  
 A `real` work array which must be dimensioned at least `2n+15` in the program that calls `dfftf`. The `wsave` array must be initialized by calling subroutine `dffti(n,wsave)` and a different `wsave` array must be used for each different value of `n`. This initialization does not have to be repeated so long as `n` remains unchanged thus subsequent transforms can be obtained faster than the first. The same `wsave` array can be used by `dfftf` and `dfftb`.  
 Contains initialization calculations which must not be destroyed between calls of subroutine `dfftf` or `dfftb`.
 

src/fftpack.f90

@@ -31,7 +31,7 @@ pure subroutine zfftf(n, c, wsave)
             import dp
             integer, intent(in) :: n
             complex(kind=dp), intent(inout) :: c(*)
-            real(kind=dp), intent(inout) :: wsave(*)
+            real(kind=dp), intent(in) :: wsave(*)
         end subroutine zfftf
 
         !> Version: experimental
@@ -42,7 +42,7 @@ pure subroutine zfftb(n, c, wsave)
             import dp
             integer, intent(in) :: n
             complex(kind=dp), intent(inout) :: c(*)
-            real(kind=dp), intent(inout) :: wsave(*)
+            real(kind=dp), intent(in) :: wsave(*)
         end subroutine zfftb
 
         !> Version: experimental
@@ -63,7 +63,7 @@ pure subroutine dfftf(n, r, wsave)
             import dp
             integer, intent(in) :: n
             real(kind=dp), intent(inout) :: r(*)
-            real(kind=dp), intent(inout) :: wsave(*)
+            real(kind=dp), intent(in) :: wsave(*)
         end subroutine dfftf
 
         !> Version: experimental
@@ -74,7 +74,7 @@ pure subroutine dfftb(n, r, wsave)
             import dp
             integer, intent(in) :: n
             real(kind=dp), intent(inout) :: r(*)
-            real(kind=dp), intent(inout) :: wsave(*)
+            real(kind=dp), intent(in) :: wsave(*)
         end subroutine dfftb
 
     end interface