From 8754ec288dc491f3a9e936e68a1fd35783c9808e Mon Sep 17 00:00:00 2001
From: Dominic Symes <dominic.symes@arm.com>
Date: Fri, 8 Dec 2023 17:45:31 +0000
Subject: Main Conformance: TANH change, SCATTER clarification

TANH can have cancellation between exp(x) and exp(-x)
for small abs(x). To allow for this, a lower bound of
0.5*exp(-normal_fraction<in_out_t>) is set for the
error bound. The TANH formula also can contain 4
exp() values, so the error bound is increased to 4
multiplied by the exp() error bound.

SCATTER output size K must be as least as great
as the number of indices W, as each index is distinct.

Change-Id: I8d1f1c866bd59d8140cf7db76404f5006a04a3f3
Signed-off-by: Dominic Symes <dominic.symes@arm.com>
---
 chapters/scatter_gather.adoc | 1 +
 1 file changed, 1 insertion(+)

(limited to 'chapters/scatter_gather.adoc')

diff --git a/chapters/scatter_gather.adoc b/chapters/scatter_gather.adoc
index 1dbda4f..d694d39 100644
--- a/chapters/scatter_gather.adoc
+++ b/chapters/scatter_gather.adoc
@@ -31,6 +31,7 @@ for_each(0 <= n < N, 0 <= w < W, 0 <= c < C) {
 The values_out tensor is set to the values_in tensor with data modified as follows: data from the input tensor is inserted at the positions specified by the indices tensor.
 N is the number of batches, W the number of indices in each batch, K the range of each index and C the number data channels for each index.
 It is not permitted to repeat the same output index within a single SCATTER operation and so each output index occurs at most once.
+It follows that K >= W.
 In use cases that require multiple updates to the same output position, these must be decomposed into multiple SCATTER operations.
 
 include::{generated}/operators/SCATTER.adoc[]
-- 
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