Add an erf based gelu op (#900)

* Erf based gelu.

* Add the erf backed gelu.

* Test the new gelu op (which is not gelu_new).

1 files changed, 3 insertions, 0 deletions

diff --git a/candle-core/src/backprop.rs b/candle-core/src/backprop.rs
index 9c8f685f..3e2ae1ed 100644
--- a/candle-core/src/backprop.rs
+++ b/candle-core/src/backprop.rs
@@ -442,6 +442,9 @@ impl Tensor {
                         *sum_grad = sum_grad.add(&arg_grad)?
                     }
                     Op::Unary(_, UnaryOp::Gelu) => Err(Error::BackwardNotSupported { op: "gelu" })?,
+                    Op::Unary(_, UnaryOp::GeluErf) => {
+                        Err(Error::BackwardNotSupported { op: "gelu-erf" })?
+                    }
                     Op::Unary(arg, UnaryOp::Relu) => {
                         let sum_grad = grads.or_insert(arg)?;
                         let relu_grad = arg.ge(&arg.zeros_like()?)?.to_dtype(arg.dtype())?;