added diagflat

Author: shivasankarka

numojo/core/array_creation_routines.mojo

@@ -541,8 +541,28 @@ fn full[
     return NDArray[dtype](shape, fill=tens_value)
 
 
-fn diagflat():
-    pass
+fn diagflat[dtype: DType](inout v: NDArray[dtype], k: Int = 0) raises -> NDArray[dtype]:
+    """
+    Generate a 2-D NDArray with the flattened input as the diagonal.
+
+    Parameters:
+        dtype: Datatype of the NDArray elements.
+
+    Args:
+        v: NDArray to be flattened and used as the diagonal.
+        k: Diagonal offset.
+
+    Returns:
+        A 2-D NDArray with the flattened input as the diagonal.
+    """
+    v.reshape(v.ndshape.ndsize, 1)
+    var n: Int= v.ndshape.ndsize + abs(k)
+    var result: NDArray[dtype]= NDArray[dtype](n, n, random=False)
+
+    for i in range(n):
+        print(n*i + i + k)
+        result.store(n*i + i + k, v.data[i])
+    return result
 
 
 fn tri():