Source: streamplot_demo.f90
Streamplots for 2D vector fields.
streamplot_demo.f90 - Source codeoutput/example/fortran/streamplot_demo/make example ARGS="streamplot_demo"

ASCII output:
Streamline Plot Demo - With Arrows
+--------------------------------------------------------------------------------+
| |
| | ^ |
| 0.9 |
| |
| \ |
| |
| 0.8 |
| | |
| < |
| |
| < \ |
| 0.6 \ |
| | |
| |
| |
| 0.5 |
| \ |
| |
| | |
| |
| 0.3 |
| |
| |
| | |
| |
| < |
| 0.2 |
| |
| | - - - - - |
| 0.0 0.2 0.3 0.5 0.6 0.8 0.9 |
+--------------------------------------------------------------------------------+
X
Y

ASCII output:
Streamline Plot Demo - Circular Flow
+--------------------------------------------------------------------------------+
| 2.0 |
| | |
| |
| | |
| 1.5 |
| | |
| | |
| 1.0 |
| | - - - - - - - - - - - - - - - - |
| | -- ---- -- - - -- - - -- - -- - -- ---- -- - - - - - ---- - - - -- -- |
| 0.5 -- - --- - - - - ----- ---- ---- -- - -- - ----- ---- - - - ---- -- - -- - |
| |-- --- - - -- ---- - - ---- - -- - -- - -- - - -- - -- - -- -- - -- -- - - |
| -- --- ------- -- - --- - ---- -- - -- - - -- - - -- -- - - -- -- -- --- -- |
| |-- ---- --- ---- - --- -- ----- - ------------ - -- ---- -- -- -- --- --- |
| | - - -- - --- ---- ------------------ ---- ------- ----- --- -- -- -- - - |
| 0.0 - - - --- - - - -- - - --------- - - -- - - - --- - - - - -- |
| | --- - -- --- -- -- ------- ---- ----------------- ---- --- - -- -- - - |
| |----- ----- -- -- --- -- --- - - ---- - - - - -- -- - ---- ------ -- -- |
| -0.5- --- -- -- - - - -- - - - - - - -- - -- - --- - -- -- - ------ -- |
| |- - -- --- - - - - -- - - - - - - - - ---- - - - - - -- -- - --- -- |
| - --- - - - - -- - - - - - - - - - - - - - - - ---- - - - --- - -- -- |
| | - - ---- - - - - - - - - - -- - - - - - - - -- - - -- ---- -- |
| | - - - - - - - - - - - - |
| -1.0 |
| | |
| | |
| -1.5 |
| | |
| | - - - - - - - - - - - - - - - - - |
| -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 |
+--------------------------------------------------------------------------------+
X
Y