How to stack several vector plots using StreamPlot?

Question

I would like to plot several stream plots as is in ref/StreamPlot (Mathematica 12).

As is reported in the section: Generate a list of stream plots of varying [Lambda]:

I did not change but it does not work as this example.

The problem is, there is field that may represent a bidimensional vector (Electric,Acoustic), this is the code.

a = 1; b = 1;  (* fixed values, constants *)

f1 = (-y  l )/(y^2 + a x^2);

f2 = ( x l )/(b y^2 + x^2);


l = {-1, 0, 1};  (* This can take several values *)

plots = MapIndexed[
  Function[{f1, f2}, 
   StreamPlot[{f1, f2}, {x, -3, 3}, {y, -3, 3}, StreamPoints -> 16, 
    StreamScale -> 0.07, 
    StreamStyle -> ColorData["SolarColors"][0.3 l[[1]]]]], l]

plotSpacing = 5;
stackPlots[plots, plotSpacing, Axes -> True, Boxed -> False, 
 Ticks -> {Automatic, Automatic, 
   MapIndexed[{plotSpacing #2[[1]], Row[{"l = ", #1}]} &, values]}]

It does not work, only the constant value is plotted. the function can not take different values as must be. This function does not evaluate the vector.Thanks!

Answer 1

Do you mean this plot?

a = 1; b = 1;(*fixed values,constants*)
f1 = (-y l)/(y^2 + a x^2);
f2 = (x l)/(b y^2 + x^2);
Function[{f1, f2}, 
  StreamPlot[{f1, f2}, {x, -3, 3}, {y, -3, 3}, StreamPoints -> 16, 
   StreamScale -> 0.07, 
   StreamStyle -> ColorData["SolarColors"][0.3 ]]] @@@ 
 Table[{f1, f2}, {l, {-1, 0, 1}}]

Table[StreamPlot[{f1, f2}, {x, -3, 3}, {y, -3, 3}, StreamPoints -> 16,
   StreamScale -> 0.07, 
  StreamStyle -> ColorData["SolarColors"][0.3 ]], {l, {-1, 0, 1}}]