updated2

Author: srinjoy933

src/sparse/stdlib_sparse_conversion.fypp

@@ -85,6 +85,18 @@ module stdlib_sparse_conversion
         #:endfor
     end interface
     public :: csr2dense
+     !! version: experimental
+    !!
+    !! Conversion from csc to dense
+    !! Enables creating a dense 2D matrix from the non-zero values stored in a CSC format
+    !! The dense matrix can be allocated on the fly if not pre-allocated by the user.
+    !! [Specifications](../page/specs/stdlib_sparse.html#sparse_conversion)
+    interface csc2dense
+        #:for k1, t1, s1 in (KINDS_TYPES)
+        module procedure :: csc2dense_${s1}$
+        #:endfor
+    end interface
+    public :: csc2dense
 
     !! version: experimental
     !!
@@ -317,6 +329,32 @@ contains
             end do
         end if
     end subroutine
+    
+    #:endfor
+
+    #:for k1, t1, s1 in (KINDS_TYPES)
+    subroutine csc2dense_${s1}$(CSC,dense)
+        type(CSC_${s1}$_type), intent(in) :: CSC
+        ${t1}$, allocatable, intent(out) :: dense(:,:)
+        integer(ilp) :: i, j
+
+        if(.not.allocated(dense)) allocate(dense(CSC%nrows,CSC%ncols),source=zero_${s1}$)
+        if( CSC%storage == sparse_full) then
+            do j = 1, CSC%ncols
+                do i = CSC%colptr(j), CSC%colptr(j+1)-1
+                    dense(CSC%row(i),j) = CSC%data(i)
+                end do
+            end do
+        else
+            do j = 1, CSC%ncols
+                do i = CSC%colptr(j), CSC%colptr(j+1)-1
+                    dense(CSC%row(i),j) = CSC%data(i)
+                    if( j == CSC%row(i) ) cycle
+                    dense(j,CSC%row(i)) = CSC%data(i)
+                end do
+            end do
+        end if
+    end subroutine
 
     #:endfor