示例：转换绘图中的单位

绘图 > 使用绘图 > 示例：转换绘图中的单位

示例：转换绘图中的单位

更改轴表达式中的单位。

1. 定义一个值域变量和带单位的函数。

2. 绘出函数图形。

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      <title class="- topic/title " wwtype:type="Paragraph" xmlns:wwtype="urn:WebWorks-Type-Schema" />
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          <traceStyle color="#FF00008B" symbol="x" line-weight="1" line-style="Solid">lines</traceStyle>
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      <graph-size width="442.6" height="254.4" />
      <axes>
        <xAxis rank="1" legend-position="PlotBoundaryBottom" start="0" end="5">
          <axisLine position="origin" positionticmark="0" legendWidth="60.93" />
          <axisGrid>
            <gridFrequency>11</gridFrequency>
            <gridLabels display="true" />
            <gridLines />
            <tickMarks display="true" />
          </axisGrid>
          <axisLabel />
          <markers />
          <numberFormat>
            <decimal precision="3" show-trailing-zeros="false" radix="dec" imaginary-value="i" />
          </numberFormat>
          <plotEquations>
            <plotEquation>
              <math>
                <id xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">x</id>
              </math>
              <math>
                <placeholder xmlns="http://schemas.mathsoft.com/math50" />
              </math>
            </plotEquation>
          </plotEquations>
          <xyDomain scale-type="linear" auto-scale="true">
            <startValue>
              <placeholder xmlns="http://schemas.mathsoft.com/math50" />
            </startValue>
            <endValue>
              <placeholder xmlns="http://schemas.mathsoft.com/math50" />
            </endValue>
          </xyDomain>
        </xAxis>
        <yAxis rank="1" legend-position="PlotBoundaryLeft" start="0" end="5">
          <axisLine position="origin" positionticmark="0" legendWidth="110.68" />
          <axisGrid>
            <gridFrequency>11</gridFrequency>
            <gridLabels display="true" />
            <gridLines />
            <tickMarks display="true" />
          </axisGrid>
          <axisLabel />
          <markers />
          <numberFormat>
            <decimal precision="3" show-trailing-zeros="false" radix="dec" imaginary-value="i" />
          </numberFormat>
          <plotEquations>
            <plotEquation>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
                  <id xml:space="preserve">x</id>
                </apply>
              </math>
              <math>
                <id labels="UNIT" xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">m</id>
              </math>
            </plotEquation>
          </plotEquations>
          <xyDomain scale-type="linear" auto-scale="true">
            <startValue>
              <placeholder xmlns="http://schemas.mathsoft.com/math50" />
            </startValue>
            <endValue>
              <placeholder xmlns="http://schemas.mathsoft.com/math50" />
            </endValue>
          </xyDomain>
        </yAxis>
      </axes>
    </xyPlot>
  </plot>
</region>

无论输入的单位为何，刻度值都以所使用的单位制的基本单位形式显示。

3. 通过从单位占位符中删除米缩写 m 并在空占位符中插入英寸缩写 in，更改绘制 y 轴表达式所采用的单位。

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    <xyPlot>
      <title class="- topic/title " wwtype:type="Paragraph" xmlns:wwtype="urn:WebWorks-Type-Schema" />
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      <traces>
        <trace resultRef="13">
          <traceStyle color="#FF00008B" symbol="x" line-weight="1" line-style="Solid">lines</traceStyle>
        </trace>
      </traces>
      <graph-size width="441.6" height="254.4" />
      <axes>
        <xAxis rank="1" legend-position="PlotBoundaryBottom" start="0" end="5">
          <axisLine position="origin" positionticmark="0" legendWidth="60.93" />
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            <gridFrequency>11</gridFrequency>
            <gridLabels display="true" />
            <gridLines />
            <tickMarks display="true" />
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          <axisLabel />
          <markers />
          <numberFormat>
            <decimal precision="3" show-trailing-zeros="false" radix="dec" imaginary-value="i" />
          </numberFormat>
          <plotEquations>
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                <id xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">x</id>
              </math>
              <math>
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              </math>
            </plotEquation>
          </plotEquations>
          <xyDomain scale-type="linear" auto-scale="true">
            <startValue>
              <placeholder xmlns="http://schemas.mathsoft.com/math50" />
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            <endValue>
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          </xyDomain>
        </xAxis>
        <yAxis rank="1" legend-position="PlotBoundaryLeft" start="0" end="200">
          <axisLine position="origin" positionticmark="0" legendWidth="111.65" />
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            <gridFrequency>11</gridFrequency>
            <gridLabels display="true" />
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            <tickMarks display="true" />
          </axisGrid>
          <axisLabel />
          <markers />
          <numberFormat>
            <decimal precision="3" show-trailing-zeros="false" radix="dec" imaginary-value="i" />
          </numberFormat>
          <plotEquations>
            <plotEquation>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
                  <id xml:space="preserve">x</id>
                </apply>
              </math>
              <math>
                <id labels="UNIT" xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">in</id>
              </math>
            </plotEquation>
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        </yAxis>
      </axes>
    </xyPlot>
  </plot>
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4. 重新绘制同一函数，但是这次不要转换单位，而是在单位占位符中添加一个缩放因子。

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        <trace resultRef="15">
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        <xAxis rank="1" legend-position="PlotBoundaryBottom" start="0" end="5">
          <axisLine position="origin" positionticmark="0" legendWidth="60.93" />
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            <gridLabels display="true" />
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          <axisLabel />
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              <math>
                <id xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">x</id>
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              </math>
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          <xyDomain scale-type="linear" auto-scale="true">
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          </xyDomain>
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        <yAxis rank="1" legend-position="PlotBoundaryLeft" start="0" end="200">
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            <gridLabels display="true" />
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            <tickMarks display="true" />
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          <axisLabel />
          <markers />
          <plotEquations>
            <plotEquation>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
                  <id xml:space="preserve">x</id>
                </apply>
              </math>
              <math>
                <id labels="UNIT" xml:space="preserve" xmlns="http://schemas.mathsoft.com/math50">in</id>
              </math>
            </plotEquation>
            <plotEquation>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
                  <id xml:space="preserve">x</id>
                </apply>
              </math>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <scale />
                  <real>0.1</real>
                  <id labels="UNIT" xml:space="preserve">m</id>
                </apply>
              </math>
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轨迹代表等值的数字。例如，第一轨迹上的第二个点就位于 79 in = 2 米处。在第二条轨迹上，则是 20 * 0.1 米 = 2 米。

5. 插入两个水平标记，以标示以上两个数据点。

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              <real xmlns="http://schemas.mathsoft.com/math50">79</real>
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              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
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              <math>
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            <plotEquation>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <id xml:space="preserve">dist</id>
                  <id xml:space="preserve">x</id>
                </apply>
              </math>
              <math>
                <apply xmlns="http://schemas.mathsoft.com/math50">
                  <scale />
                  <real>0.1</real>
                  <id labels="UNIT" xml:space="preserve">m</id>
                </apply>
              </math>
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        </yAxis>
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    </xyPlot>
  </plot>
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刻度和注释值都没有单位。仅轴表达式可含有单位。