Add scal!(n,a,X) (#40020)

Author: dbrueg

stdlib/LinearAlgebra/src/blas.jl

@@ -217,16 +217,22 @@ end
 ## scal
 
 """
+    scal!(n, a, X)
     scal!(n, a, X, incx)
 
 Overwrite `X` with `a*X` for the first `n` elements of array `X` with stride `incx`. Returns `X`.
+
+Uses `stride1(X)` as stride if `incx` is not passed.
 """
 function scal! end
 
 """
+    scal(n, a, X)
     scal(n, a, X, incx)
 
 Return `X` scaled by `a` for the first `n` elements of array `X` with stride `incx`.
+
+Uses `stride(X,1)` as stride if `incx` is not passed.
 """
 function scal end
 
@@ -242,9 +248,12 @@ for (fname, elty) in ((:dscal_,:Float64),
                   n, DA, DX, incx)
             DX
         end
+
+        scal!(n::Integer, DA::$elty, DX::AbstractArray{$elty}) = scal!(n,DA,DX,stride(DX,1))
     end
 end
 scal(n, DA, DX, incx) = scal!(n, DA, copy(DX), incx)
+scal(n, DA, DX) = scal!(n, DA, copy(DX))
 
 ## dot