示例：绘制不等式和分段函数

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示例：绘制不等式和分段函数

使用绘图显示不等式和分段函数。

不等式

1. 在空白绘图中，在 y 轴表达式中输入不等式，在 x 轴表达式中输入相应的自变量。

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                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <greaterThan />
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                    <real>2</real>
                    <id>r</id>
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                  <real>5</real>
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              <math>
                <placeholder xmlns="http://schemas.mathsoft.com/math50" />
              </math>
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        </yAxis>
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由于不等式为布尔表达式，PTC Mathcad 可同时绘制状态为真的 r 值 (>2.5) 和状态为假的 r 值 (<2.5)。当状态为真时，不等式等于 1，当状态为假时，不等式等于 0。

2. 使用“与”运算符将第二个不等式附加到第一个不等式。

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        <yAxis legend-position="PlotBoundaryLeft" rank="1">
          <axisLine position="origin" positionticmark="5" />
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                <apply xmlns="http://schemas.mathsoft.com/math50">
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                    <apply>
                      <greaterThan />
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                        <scale />
                        <real>2</real>
                        <id>r</id>
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                      <real>5</real>
                    </apply>
                  </parens>
                  <parens>
                    <apply>
                      <lessThan />
                      <id>r</id>
                      <apply>
                        <div />
                        <real>20</real>
                        <real>3</real>
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                    </apply>
                  </parens>
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                <placeholder xmlns="http://schemas.mathsoft.com/math50" />
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分段函数

在自身的域中分布不均匀的函数称为分段函数。要绘制分段函数，需要使用内置条件函数 if。

1. 定义函数并在特定范围内进行绘制。

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          <axisLine position="ticknumberlock" positionticmark="2" />
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2. 定义并绘制只有在 f(x) > 0 时才等于 f(x) 的分段函数。

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3. 使用“与”运算符定义绘制 f(x) 时的 x 的范围。对于其他范围的 x 值，绘制函数 f 的负值部分。

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