# 运算

## 输入

The inputs of the node are dynamic. Some inputs are only available in certain operations. For instance, the Addend input is only available in the Multiply Add operator.

Epsilon

## 属性

Returns the positive remainder of a division operation.

The output value is moved between 0.0 and the Scale based on the input value.

## 示例

### 自定义Z深度通道节点设置

This example has one scene input by the top Render Layers node, which has a cube that is about 10 units from the camera. The bottom Render Layers node inputs a scene with a plane that covers the left half of the view and is 7 units from the camera. Both are fed through their respective Map Value nodes to divide the Z-buffer by 20 (multiply by 0.05, as shown in the Size field) and clamped to be a min/max of 0.0/1.0 respectively.

For the minimum function, the node selects those Z values where the corresponding pixel is closer to the camera; so it chooses the Z values for the plane and part of the cube. The background has an infinite Z value, so it is clamped to 1.0 (shown as white). In the maximum example, the Z values of the cube are greater than the plane, so they are chosen for the left side, but the plane Render Layers Z are infinite (mapped to 1.0) for the right side, so they are chosen.

### 使用正弦功能得到不断循环的变化数

Since the sine function can put out values between (-1.0 to 1.0), the Map Value node scales that to 0.0 to 1.0 by taking the input (-1 to 1), adding 1 (making 0 to 2), and multiplying the result by one-half (thus scaling the output between 0 to 1). The default Color Ramp converts those values to a gray-scale. Thus, medium gray corresponds to a 0.0 output by the sine, black to -1.0, and white to 1.0. As you can see, $$sin(pi/ 2) = 1.0$$. Like having your own visual color calculator! Animating this node setup provides a smooth cyclic sequence through the range of grays.

### 提亮（缩放）通道

This example has a Math (Multiply) node increasing the luminance channel (Y) of the image to make it brighter. Note that you should use a Map Value node with min() and max() enabled to clamp the output to valid values. With this approach, you could use a logarithmic function to make a high dynamic range image. For this particular example, there is also a Brightness/Contrast node that might give simpler control over brightness.

### 重新限定颜色选择（色调分离）

To split up a continuous range of values between 0 and 1 to certain set of values, the following function is used: $$round(x × n - 0.5) / (n - 1)$$, where "n" is the number of possible output values, and "x" is the input pixel color. Read more about this function.

In the case of a color image, you need to split it into separate RGB channels using Separate/Combine RGBA nodes and perform this operation on each channel independently.