Graphs of functions with two or more variables can be 'sliced', affording a more detailed view of function behavior in the plane of the slice. Slice planes are always normal to a coordinate axis, and intercept that axis at a point on the coordinate grid.

Using Graph Slicing to Explore Multivariate Functions

1. Initiate graph slicing by first selecting the Trace item from the global popup menu; this places the display in reading mode (see Plot Markup). The same projection plane used to read function values (trace plane) doubles as the slice plane for 'slicing'.
2. Using the radio buttons and spinner control at the foot of the graphics legend, position the trace plane to produce the desired slice, then type ctrl+enter to convert the 'pending slice' into an actual one. This action 'locks' the slice variable at its current value, and replaces the graph with a new one depicting function values confined to the plane of the slice.
   Slicing can be very disorienting; the new axes – labeled by the remaining [unlocked] independent variables – serve as valuable guides to interpreting the updated display.
   Slicing applies to any graph with dimension higher than one; thus, density plots (dimension 3) can be sliced once to yield surface plots (dimension 2), then sliced again to yield line plots (dimension 1). At any stage, the previous slice can be undone by typing shift+ctrl+enter.
3. When slicing is in effect, the value of the last 'locked' variable can be adjusted on-the-fly, and the display is updated accordingly. Use the keyboard shortcut alt+G to move the actual data slice ahead one unit on the coordinate grid, and shift+alt+G to move it back one unit.
   Stepping through data slices this way is a very powerful technique for exploring functions of several variables.

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