create submodule

Author: perazz

src/stdlib_linalg.fypp

@@ -24,6 +24,8 @@ module stdlib_linalg
   public :: lstsq_space
   public :: solve_lstsq
   public :: trace
+  public :: svd
+  public :: svdvals
   public :: outer_product
   public :: kronecker_product
   public :: cross_product
@@ -456,6 +458,58 @@ module stdlib_linalg
     #:endfor
   end interface  
 
+  ! Singular value decomposition
+  interface svd
+    !! version: experimental 
+    !!
+    !!### Description
+    !! 
+    !! 
+
+    #:for rk,rt,ri in RC_KINDS_TYPES
+    #:if rk!="xdp"
+    module subroutine stdlib_linalg_svd_${ri}$(a,s,u,vt,overwrite_a,full_matrices,err)
+         !> Input matrix A[m,n]
+         ${rt}$, intent(inout), target :: a(:,:)
+         !> Array of singular values
+         real(${rk}$), intent(out) :: s(:)
+         !> The columns of U contain the eigenvectors of A A^T
+         ${rt}$, optional, intent(out), target :: u(:,:)
+         !> The rows of V^T contain the eigenvectors of A^T A
+         ${rt}$, optional, intent(out), target :: vt(:,:)
+         !> [optional] Can A data be overwritten and destroyed?
+         logical(lk), optional, intent(in) :: overwrite_a
+         !> [optional] full matrices have shape(u)==[m,m], shape(vh)==[n,n] (default); otherwise
+         !> they are shape(u)==[m,k] and shape(vh)==[k,n] with k=min(m,n)
+         logical(lk), optional, intent(in) :: full_matrices
+         !> [optional] state return flag. On error if not requested, the code will stop
+         type(linalg_state_type), optional, intent(out) :: err
+      end subroutine stdlib_linalg_svd_${ri}$
+    #:endif
+    #:endfor     
+  end interface svd
+
+  ! Singular values
+  interface svdvals
+    !! version: experimental 
+    !!
+    !!### Description
+    !! 
+    !! 
+    #:for rk,rt,ri in RC_KINDS_TYPES
+    #:if rk!="xdp"
+    module function stdlib_linalg_svdvals_${ri}$(a,err) result(s)
+         !> Input matrix A[m,n]
+         ${rt}$, intent(in), target :: a(:,:)
+         !> [optional] state return flag. On error if not requested, the code will stop
+         type(linalg_state_type), optional, intent(out) :: err
+         !> Array of singular values
+         real(${rk}$), allocatable :: s(:)
+      end function stdlib_linalg_svdvals_${ri}$
+    #:endif
+    #:endfor             
+  end interface svdvals  
+
 contains
 
 

src/stdlib_linalg_svd.fypp

@@ -1,6 +1,6 @@
 #:include "common.fypp"
 #:set RC_KINDS_TYPES = REAL_KINDS_TYPES + CMPLX_KINDS_TYPES
-module stdlib_linalg_svd
+submodule(stdlib_linalg) stdlib_linalg_svd
 !! Singular-Value Decomposition    
      use stdlib_linalg_constants
      use stdlib_linalg_lapack, only: gesdd
@@ -9,30 +9,8 @@ module stdlib_linalg_svd
      implicit none(type,external)
 
      character(*), parameter :: this = 'svd'
-
-     !> Singular value decomposition
-     public :: svd
-     !> Singular values
-     public :: svdvals
-
-     ! Numpy: svd(a, full_matrices=True, compute_uv=True, hermitian=False)
-     ! Scipy: svd(a, full_matrices=True, compute_uv=True, overwrite_a=False, check_finite=True, lapack_driver='gesdd')
-
-     interface svd
-        #:for rk,rt,ri in RC_KINDS_TYPES
-        #:if rk!="xdp"
-        module procedure stdlib_linalg_svd_${ri}$
-        #:endif
-        #:endfor
-     end interface svd
-
-     interface svdvals
-        #:for rk,rt,ri in RC_KINDS_TYPES
-        #:if rk!="xdp"
-        module procedure stdlib_linalg_svdvals_${ri}$
-        #:endif
-        #:endfor
-     end interface svdvals
+     
+     !> List of internal GESDD tasks: 
 
      !> Return full matrices U, V^T to separate storage
      character, parameter :: GESDD_FULL_MATRICES   = 'A'
@@ -46,9 +24,6 @@ module stdlib_linalg_svd
      !> Do not return either U or VT (singular values array only)
      character, parameter :: GESDD_SINGVAL_ONLY    = 'N'
 
-     
-
-
      contains
 
      !> Process GESDD output flag
@@ -87,7 +62,7 @@ module stdlib_linalg_svd
      #:if rk!="xdp"
 
      !> Singular values of matrix A
-     function stdlib_linalg_svdvals_${ri}$(a,err) result(s)
+     module function stdlib_linalg_svdvals_${ri}$(a,err) result(s)
          !> Input matrix A[m,n]
          ${rt}$, intent(in), target :: a(:,:)
          !> [optional] state return flag. On error if not requested, the code will stop
@@ -115,7 +90,7 @@ module stdlib_linalg_svd
      end function stdlib_linalg_svdvals_${ri}$
 
      !> SVD of matrix A = U S V^T, returning S and optionally U and V^T
-     subroutine stdlib_linalg_svd_${ri}$(a,s,u,vt,overwrite_a,full_matrices,err)
+     module subroutine stdlib_linalg_svd_${ri}$(a,s,u,vt,overwrite_a,full_matrices,err)
          !> Input matrix A[m,n]
          ${rt}$, intent(inout), target :: a(:,:)
          !> Array of singular values
@@ -285,4 +260,4 @@ module stdlib_linalg_svd
      #:endif
      #:endfor
 
-end module stdlib_linalg_svd
+end submodule stdlib_linalg_svd

test/linalg/test_linalg_svd.fypp

@@ -4,10 +4,8 @@
 module test_linalg_svd
     use testdrive, only: error_type, check, new_unittest, unittest_type
     use stdlib_linalg_constants    
-    use stdlib_linalg, only: diag
-    use stdlib_linalg_svd, only: svd,svdvals
+    use stdlib_linalg, only: diag,svd,svdvals
     use stdlib_linalg_state, only: linalg_state_type
-
     implicit none (type,external)
 
     public :: test_svd