.NODE

Setting Log or Semilog Scales

Problem

You'd like to use log scales instead of linear scales.

Solution

Select the axis you'd like to set to log scale and open the Format Axis dialog, as described in Recipe 4.4. Go to the Scale tab and check the Logarithmic Scale option (see Figure 4-11).

Discussion

You can create a log chart by setting both axes to logarithmic scale, or you can create a semilog chart by setting only one axis to logarithmic scale.

Consider the data shown in Figure 4-12 as an example. This data represents the reduction in concentration of cyclopropane as a function of reaction time (the cyclopropane gets converted to propane gas).

Figure 4-12. Reaction time plot

This plot of concentration versus reaction time shows the characteristic logarithmic form of so-called first-order reactions. Changing the vertical axis to logarithmic scale as described earlier results in the chart shown in Figure 4-13.

Notice that the plotted line is now linear. Plotting the data in this form facilitates estimating the rate constant for such a reaction, since the slope of the line can be determined by using the simple equation for a straight line.

Figure 4-13. Reaction time plotted on semilog chart

 

See Also

See Chapter 8 to learn how to perform least-squares curve fitting in Excel.

Using Excel

Getting Acquainted with Visual Basic for Applications

Collecting and Cleaning Up Data

Charting

Statistical Analysis

Time Series Analysis

Mathematical Functions

Curve Fitting and Regression

Solving Equations

Numerical Integration and Differentiation

Solving Ordinary Differential Equations

Solving Partial Differential Equations

Performing Optimization Analyses in Excel

Introduction to Financial Calculations

Index





Excel Scientific and Engineering Cookbook
Excel Scientific and Engineering Cookbook (Cookbooks (OReilly))
ISBN: 0596008791
EAN: 2147483647
Year: N/A
Pages: 206
Authors: David M Bourg
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