Skip to content

$StreamColorBar

Status: Experimental

present and registered, but lightly documented and not yet covered by dedicated tests.

Description

$StreamColorBar[speed_min, speed_max]

Internal StreamPlot metadata. Instructs the renderer to draw a vertical speed color scale bar (dark blue = slow, yellow = fast). Not intended for direct use.

Examples (2)

Every input below was run against the current Mathilda build and its output recorded.

Applications (2)

ContourPlot embeds one colour-bar node

In[1]:= Count[ContourPlot[x^2 + y^2, {x, -1, 1}, {y, -1, 1}, PlotLegends -> Automatic], _$StreamColorBar, Infinity]
Out[1]= 1

An inert metadata head

In[2]:= Head[$StreamColorBar[-Pi, Pi, "Cyclic"]]
Out[2]= $StreamColorBar

Implementation notes

Definition. $StreamColorBar is an internal metadata head — not a user-facing function. It records the data needed to draw a colour-scale bar beside a plot: $StreamColorBar[min, max] for a density/contour scale, or $StreamColorBar[min, max, colourFnOrName] for a complex-plot phase wheel. It is emitted by the plot builders and read back by the renderer.

Representation. A bare EXPR_SYMBOL head (interned SYM_StreamColorBar, Protected). contourplot.c appends $StreamColorBar[zmin, zmax, ...] to the Graphics[...] option list when PlotLegends -> Automatic; complexplot.c appends $StreamColorBar[-Pi, Pi, cfn_or_"Cyclic"] for its phase bar; render.c's find_stream_colorbar locates the node in the option list and draws the bar.

Usage & limits. Internal plumbing: a user never writes $StreamColorBar directly, and it is meaningful only as an item in a graphics option list. Evaluated on its own it stays symbolic (no evaluation rule). It is documented here only because it is reachable from the symbol table (Names["*"]).

Internal symbol — shown below only structurally; it has no standalone mathematical example.

Attributes: Protected.

References

Notes & additional examples

Notes

$StreamColorBar[min, max] (or $StreamColorBar[min, max, colourFnOrName]) is an internal metadata head — not something you write by hand. It records the data a colour-scale bar needs: ContourPlot / DensityPlot append $StreamColorBar[zmin, zmax, ...] when PlotLegends -> Automatic, and ComplexPlot appends $StreamColorBar[-Pi, Pi, cfn] for its phase wheel; the renderer reads the node back and draws the bar.

It is Protected, has no evaluation rule, and stays symbolic on its own. It is listed here only because it is reachable from the symbol table. The examples above are structural — this symbol has no standalone mathematical meaning.