北京环中睿驰科技有限公司 http://www.reahsoft.com.cn provide for graphing the results. Sorting
Sort operation sorts one or more 1D numeric or text data sets in ascending or descending order. Multiple sort keys are supported (for cases where the first key has identical values). MakeIndex and IndexSort are also provided for extra flexibility. Extraction
The Extract operation makes it easy to extract subsets of data that correspond to specific criteria. For example,
Extract/O source,dest,source>10 && source<20
creates a new data set named dest containing values from soruce that are between 10 and 20. You can also find the index values where the expression is true so you can access the subset in place. Smoothing
Igor has three built-in algorithms. Each one effectively precomputes smoothing coefficients according to the smoothing parameters, and then replaces each data wave with the convolution of the wave with the coefficients. The bulit-in methods are:
? Binomial Smoothing: The Binomial smoothing operation is a Gaussian
filter. It is the sharpest filter that will not cause ringing on a step or impulse.
? Savitzky-Golay Smoothing: Savitzky-Golay smoothing uses a different
set of precomputed coefficients popular in the field of chemistry. It is a type of Least Squares Polynomial smoothing. The amount of smoothing is controlled by two parameters: the polynomial order and the number of points used to compute each smoothed output value.
? Box Smoothing: Box smoothing is similar to a moving average, except
that an equal number of points before and after the smoothed value are averaged together with the smoothed value. In addition to built-in smoothing, you can perform smoothing (or any other finite impulse response type filter) using your own coefficients with the SmoothCustom operation. Each smooth type, including SmoothCustom, can pick from several end-effect algorithms
2.7 数据分析函数
Igor includes several operations that work on functions rather than discrete data points. These operations include
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北京环中睿驰科技有限公司 http://www.reahsoft.com.cn Plotting of functions Making a graph of a
function in Igor is easy. For simple expressions, use arithmetic expressions entered on the command line. Igor's programming language allows arbitrarily complex non-linear functions expressed as
user-defined functions that can be used to make a graph.
Differential Equations Numerically solve ordinary differential equations, making possible
simulations of dynamic systems. Optimization
Use the Optimize operation to find minima and maxima of functions expressed using Igor's built-in language. Optimize functions of any number of dimensions, using a choice of methods including simulated annealing. Function Roots
Use the FindRoots operation to find roots of functions expressed using Igor's built-in language. You can use Igor to find N-dimensional roots of systems of equations.
The FindRoots operation can also be used to find complex roots of polynomials. Integration of Functions
Find numeric integrals of continuous functions using a choice of methods. By nesting integrations, you can integrate an N-dimensional function.
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北京环中睿驰科技有限公司 http://www.reahsoft.com.cn
2.8 图形数据探测（Exploration）
Because IGOR's 2D graphs are so fast, you can quickly explore large data sets by zooming in and out on portions of a graph. You can drag a marqee selection around an area of interest and then click in the center to access a popup menu to expand or contract about that area. Here is an example:
And here is the result after choosing expand:
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北京环中睿驰科技有限公司 http://www.reahsoft.com.cn Before choosing the popup menu, you can adjust the selection by dragging the marquee's handles. After zooming in on a region of interest, you can pan around in all directions.
Starting with version 6.1, you can hover your mouse over a point on an axis and use the mouse wheel to zoom in or zoom out about that point.
An even zippier tool is provided as a bulit-in procedure package that makes an copy of your graph with an expanded view of your data that follows the cursor as you move the mouse pointer over the original graph. You can experience the quickness of this tool for yourself by downloading the demo version of IGOR (anonymous download -- no registration or forms to fill out) and then following these instructions:
1. Start IGOR and either:
a. Load and graph your own data or
b. Load any of the example experiments with graphs of large data sets
or
c. Create synthetic data by copying these lines...
d. Make/N=10000 data1;SetScale x,0,10e-3,\e. data1= 2+2*cos(x*300)+10*exp(-(1e4*(x-3e-3))^2) +
1*exp(-(1e4*(x-6e-3))^2) + 0.3*exp(-(1e4*(x-6.2e-3))^2) + gnoise(0.03) f. Display data1
...and then executing them in IGOR. In IGOR, type CTRL-J (Windows, cmd-J Mac) to bring the command window forward, paste and then press return.
2. With the graph frontmost, from the menu bar, choose
Graph->Packages->Graph Magnifier.
3. In the resulting control panel, click Do It.
4. Move your mouse over the data in the original graph.
5. When finished exploring, click the Done button that was added to your
original graph. Info Box and Cursors
You can put an information box on a graph by choosing Show Info from the Graph menu while the graph is the target window. An info box displays a precise readout of values and also provides a convenient way to specify a region of interest for operations such as curve fitting.
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