---
title: "ClikaRT::ops::log_sigmoid"
sidebar_label: "log_sigmoid"
description: "Logarithm of the sigmoid, computed stably. \\[ \\mathrm{log\\_sigmoid}(x) = \\log\\frac{1}{1 + e^{-x}} = -\\,\\mathrm{softplus}(-x) \\] ClikaRT::Error when the input's dtype is not served for this operation (…"
---

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<span class="api-kind api-kind--function">function</span>

## log\_sigmoid() {#log_sigmoid}

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[`Tensor`](../Tensor.md) **`log_sigmoid`**([`Tensor`](../Tensor.md) `input`)

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Logarithm of the sigmoid, computed stably.

$$
\mathrm{log\_sigmoid}(x) = \log\frac{1}{1 + e^{-x}} = -\,\mathrm{softplus}(-x)
$$

**Throws**

- `ClikaRT::Error`: when the input's dtype is not served for this operation (the machine-readable reason rides `code_name()`).

**Returns:** a new tensor, same shape and dtype as `input`.

```cpp
auto y = ClikaRT::ops::log_sigmoid(x);
```

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Declared in `ClikaRT/compute/ops.h`, line 911

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