This function f = x*Log[y]
is defined for all x
and for y>0
f = x*Log[y];
fdomain = FunctionDomain[f, {x, y}]
so I expected StreamPlot
to only show streams for y>0
only, even if the range given in the command itself includes negative values. (may be one did not notice the y range includes something outside the domain).
But the stream plots are all missing from y=0
to y=1
and then start above that.
Why are stream lines missing from y=0..1
?
f = x*Log[y];
p = StreamPlot[{1, f}, {x, 0, 3}, {y, -1, 3},
Axes -> True, Frame -> False, AxesOrigin -> {0, 0}
]
They show up, when changing the y
range to start from zero:
f=x*Log[y];
p = StreamPlot[{1,f},{x,0,3},{y,0,3},
Axes -> True,Frame -> False,AxesOrigin->{0,0}
]
Compare to Maple, for same function and same plot range, it shows correctly the streams for 0..1
for y
even though the range asked for starts at -1
f:=x*ln(y);
plots:-fieldplot([1,f],x=0..3,y=-1..3,fieldstrength=fixed);
Mathematica 11.3 on Linux
{y,0,3}
and setPlotRange
to whatever you want. That's for a workaround, if you need to know why, I'd ask WRI Support. $\endgroup$