feat(frontends): Implement rfft in PaddlePaddle frontend and fix fft …

…for Tensorflow backend (#19454)

Co-authored-by: hmahmood24 <[email protected]>

ivy/functional/backends/tensorflow/experimental/layers.py

@@ -648,7 +648,9 @@ def _ifft_norm(
         raise ivy.utils.exceptions.IvyError(f"Unrecognized normalization mode {norm}")
 
 
-@with_supported_dtypes({"2.13.0 and below": ("complex",)}, backend_version)
+@with_supported_dtypes(
+    {"2.13.0 and below": ("complex", "float32", "float64")}, backend_version
+)
 def fft(
     x: Union[tf.Tensor, tf.Variable],
     dim: int,
@@ -658,6 +660,11 @@ def fft(
     n: Union[int, Tuple[int]] = None,
     out: Optional[Union[tf.Tensor, tf.Variable]] = None,
 ) -> Union[tf.Tensor, tf.Variable]:
+    # ToDo: Remove conversion from float to complex when casting mode is working
+    if x.dtype == "float32":
+        x = tf.cast(x, tf.complex64)
+    elif x.dtype == "float64":
+        x = tf.cast(x, tf.complex128)
     if not isinstance(dim, int):
         raise ivy.utils.exceptions.IvyError(
             f"Expecting <class 'int'> instead of {type(dim)}"

ivy/functional/frontends/paddle/fft.py

@@ -234,6 +234,12 @@ def irfftn(x, s=None, axes=None, norm="backward", name=None):
     return result_t
 
 
+@with_supported_dtypes({"2.5.1 and below": ("float32", "float64")}, "paddle")
+@to_ivy_arrays_and_back
+def rfft(x, n=None, axis=-1, norm="backward", name=None):
+    return ivy.dft(x, axis=axis, inverse=False, onesided=True, dft_length=n, norm=norm)
+
+
 @to_ivy_arrays_and_back
 def rfftfreq(n, d=1.0, dtype=None, name=None):
     dtype = ivy.default_dtype()

ivy_tests/test_ivy/test_frontends/test_paddle/test_fft.py

@@ -354,6 +354,47 @@ def test_paddle_irfftn(
     )
 
 
+# rfft
+@handle_frontend_test(
+    fn_tree="paddle.fft.rfft",
+    dtype_input_axis=helpers.dtype_values_axis(
+        available_dtypes=helpers.get_dtypes("valid"),
+        min_num_dims=1,
+        min_dim_size=2,
+        shape=helpers.get_shape(
+            min_num_dims=1,
+            max_num_dims=2,
+            min_dim_size=2,
+            max_dim_size=4,
+        ),
+        large_abs_safety_factor=12,
+        small_abs_safety_factor=12,
+        safety_factor_scale="log",
+        force_int_axis=True,
+        valid_axis=True,
+        allow_neg_axes=True,
+    ),
+    norm=st.sampled_from(["backward", "ortho", "forward"]),
+    n=st.integers(min_value=2, max_value=10) | st.none(),
+)
+def test_paddle_rfft(
+    dtype_input_axis, norm, n, frontend, backend_fw, test_flags, fn_tree, on_device
+):
+    input_dtype, x, axis = dtype_input_axis
+    helpers.test_frontend_function(
+        input_dtypes=input_dtype,
+        frontend=frontend,
+        backend_to_test=backend_fw,
+        test_flags=test_flags,
+        fn_tree=fn_tree,
+        on_device=on_device,
+        x=x[0],
+        n=n,
+        axis=axis,
+        norm=norm,
+    )
+
+
 @handle_frontend_test(
     fn_tree="paddle.fft.rfftfreq",
     n=st.integers(min_value=1, max_value=1000),