XY
The xy plotting and analysis window is opened by choosing the XY menu
option from the NMRView control panel. Any data accessible with the command
interpreter in NMRView can be placed in a data array that
can be plotted in this XY plotting window. Nonlinear
regression routines are also available to fit the data
with a variety of equations commonly used in NMR
analysis.
The data can be imported into the xy arrays and the plot limits can be specified using the
xy command.
When you choose this option two windows will
open. One is for viewing the xy graph, and one for
controlling the display and analysis of data in the
graph.
The XY Control Window has features to
allow for the control of the display and analysis of data
in the XY plot window.
- Equations
- Pull down menu used to select the desired equation to fit
to the data.
The equations specified as Lineshape G, Lineshape GJ and Lineshape GA are for fitting data to a gaussian lineshape model with no J-splitting, with in-phase splitting and with anti-phase splitting, respectively.
- Data
- The fitted data is reported in three colums, Best, Max, and Min in that order.
- Best
- These entries are the best fit values to each of the parameters
in the equation (A,B,C ...).
- Min
- The lower value for the specified confidence interval.
- Max
- The upper value for the specified confidence interval.
- Control
- The fitting and display of data is controlled by the following buttons.
- Close
- Close up XY panels.
graph.
- Fit
- This command causes a non-linear curve fit to
be done to the data stored in the xy data array. The
equation fitted is that specified in the equation pull
down menu. The xy data and a line corresponding to the
fitted parameters are displayed on the xy graph. The
best fit parameters are displayed in the xy control
window. Confidence intervals are calculated using a Monte-Carlo method
similar to that
described in Numerical Recipes (Press et al.). The data is fitted once, and then simulated data is generated
by adding gaussian noise to data simulated with the best fit parameters.
This simulated data is then fit to the same equation, with the best fit
parameters as starting values. The process is repeated (typically 100 times).
The array of values for each parameter is sorted and the two values (min and
max) are chosen that bracket a specified percentage of the data. These values
are reported in the Min and Max fields for each parameter.
- Display
- This command displays in the xy graph
window the data currently in the xy data array. The data
are not fit with an equation.
- Clear
- This command clears the xy
- Plot
- This command generates
a postscript file "xy.ps" of the current plot and sends it
to the default printer.