# Slice 2d.m

From Spinach Documentation Wiki

Contour plot slicing utility with non-linear adaptive contour spacing. Calls plot_2d.m and allows slice extraction. Syntax:

plot_2d(spin_system,spectrum,parameters,ncont,delta,k,ncol,m,signs)

The following functions are used to compute contour levels:

cont_levs_pos=delta(2)*xmax*linspace(0,1,ncont).^k+xmax*delta(1); cont_levs_neg=delta(2)*xmin*linspace(0,1,ncont).^k+xmin*delta(1);

where:

* xmax and xmin are calculated from the spectrum;

* delta is the minimum and maximum elevation (as a fraction of total intensity) of the contours above the baseline. A reasonable value for most 2D spectra is [0.02 0.2 0.02 0.2]. The first pair of num- bers refers to the positive contours and the second pair to the negative ones.

* ncont is the number of contours, a reasonable value is 20.

* k controls the curvature of the contour spacing function: k=1 corresponds to linear spacing and k>1 bends the spacing curve to increase the sampling density near the baseline. A reasonable value is 2;

* ncol is a number of colors in the colormap (around 256 is fine);

* m is the curvature of the colormap: m=1 corresponds to a linear color ramp into the red for positive contours and into the blue for negative contours. A reasonable value for high-contrast plotting is 6.

* signs can be set to 'positive', 'negative' or 'both' - this will cause the corresponding contours to be plotted.

The following subfields are required inthe parameters structure:

parameters.sweep one or two sweep widths, Hz

parameters.spins cell array with one ot two character strings specifying the working spins.

parameters.offset one or two transmitter offsets, Hz

parameters.axis_units axis units ('ppm','Hz','Gauss')