Configuration Reference

DifferentialLab is configured via a .env file in the project root. Copy .env.example to .env to get started, or use the in-app Configuration dialog (Main Menu > Configuration) which writes the file for you.

After saving through the dialog the application restarts automatically.

UI Theme

Variable	Type	Default	Description
`UI_BACKGROUND`	str	`#181818`	Main background colour (hex).
`UI_FOREGROUND`	str	`#CCCCCC`	Default text colour (hex).
`UI_BUTTON_BG`	str	`#1F1F1F`	Button / input background colour (hex).
`UI_BUTTON_WIDTH`	int	`14`	Width of main-menu buttons in characters.
`UI_BUTTON_FG`	str	`lime green`	Primary button text colour.
`UI_BUTTON_FG_CANCEL`	str	`red2`	Cancel / destructive button text colour.
`UI_BUTTON_FG_ACCENT2`	str	`yellow`	Secondary accent button text colour.
`UI_FONT_SIZE`	int	`16`	Base font size in points.
`UI_FONT_FAMILY`	str	`Bahnschrift`	Font family for the interface.
`UI_PADDING`	int	`8`	Padding in pixels between UI elements.

Colours accept any Tk colour name (e.g. lime green, crimson) or a hex code (#RRGGBB).

UI Tooltips

Variable	Type	Default	Description
`UI_TOOLTIP_DELAY_MS`	int	`500`	Delay in milliseconds before showing a tooltip.
`UI_TOOLTIP_WRAPLENGTH`	int	`350`	Maximum width in pixels before tooltip text wraps.
`UI_TOOLTIP_PADX`	int	`8`	Horizontal padding inside tooltip.
`UI_TOOLTIP_PADY`	int	`4`	Vertical padding inside tooltip.

Plot Style

Variable	Type	Default	Description
`PLOT_FIGSIZE_WIDTH`	int	`12`	Plot width in inches.
`PLOT_FIGSIZE_HEIGHT`	int	`6`	Plot height in inches.
`DPI`	int	`100`	Dots per inch (50–1000).
`PLOT_SHOW_TITLE`	bool	`true`	Show a title above the plot.
`PLOT_SHOW_GRID`	bool	`true`	Draw a background grid.
`PLOT_LINE_COLOR`	str	`royalblue`	Colour of the main solution curve.
`PLOT_LINE_WIDTH`	float	`1.5`	Line thickness in points.
`PLOT_LINE_STYLE`	str	`-`	`-` solid, `--` dashed, `-.` dash-dot, `:` dotted.
`PLOT_COLOR_SCHEME`	str	`Set1`	Matplotlib colormap for extra derivatives.

Plot Markers

Variable	Type	Default	Description
`PLOT_MARKER_FORMAT`	str	`o`	`o` circle, `s` square, `^` triangle, `d` diamond, `*` star.
`PLOT_MARKER_SIZE`	int	`3`	Marker size in points.
`PLOT_MARKER_FACE_COLOR`	str	`crimson`	Marker fill colour.
`PLOT_MARKER_EDGE_COLOR`	str	`crimson`	Marker edge colour.

Plot Phase-Space

Variable	Type	Default	Description
`PLOT_PHASE_START_COLOR`	str	`green`	Colour of the start marker in phase-space plots.
`PLOT_PHASE_END_COLOR`	str	`red`	Colour of the end marker in phase-space plots.
`PLOT_PHASE_MARKER_SIZE`	int	`8`	Size of start/end markers in phase-space plots.

Plot Fonts

Configured directly under Plot Style in the Configuration dialog.

Variable	Type	Default	Description
`FONT_FAMILY`	str	`serif`	Font family for matplotlib plots. Options: `serif`, `sans-serif`, `monospace`, `cursive`, `fantasy`.
`FONT_TITLE_SIZE`	str	`xx-large`	Title font size (matplotlib size string).
`FONT_TITLE_WEIGHT`	str	`semibold`	Title font weight. Options: `normal`, `bold`, `light`, `semibold`, `heavy`.
`FONT_AXIS_SIZE`	int	`16`	Axis label font size in points.
`FONT_AXIS_STYLE`	str	`italic`	Axis label font style. Options: `normal`, `italic`, `oblique`.
`FONT_TICK_SIZE`	int	`12`	Tick label font size in points.

Plot 3D / Contour

Variable	Type	Default	Description
`PLOT_SURFACE_CMAP`	str	`viridis`	Matplotlib colormap for 3D surface and contour plots.
`PLOT_CONTOUR_LEVELS`	int	`20`	Number of contour levels in 2D contour plots.
`PLOT_GRID_ALPHA`	float	`0.3`	Transparency of the grid lines (0–1).
`PLOT_SURFACE_ALPHA`	float	`0.9`	Transparency of 3D surfaces (0–1).
`PLOT_COLORBAR_SHRINK`	float	`0.6`	Shrink factor for the colorbar (0–1).

Plot Animation

Variable	Type	Default	Description
`PLOT_ANIMATION_LINE_WIDTH`	float	`2.0`	Line width for vector animation plot.
`PLOT_VLINES_LINE_WIDTH`	float	`1.5`	Line width for vertical lines in animation.
`PLOT_VLINES_ALPHA`	float	`0.6`	Transparency of vertical lines (0–1).
`PLOT_ANIMATION_Y_MARGIN`	float	`0.1`	Margin added to y-axis limits in animation.
`ANIMATION_MAX_FPS`	int	`30`	Maximum frames per second for animation playback.

Solver Defaults

The default integration method is the first in the available list (RK45). Use the Parameters dialog to select a different method per run.

Variable	Type	Default	Description
`SOLVER_MAX_STEP`	float	`0.0`	Maximum step size (0 = automatic).
`SOLVER_RTOL`	float	`1e-8`	Relative tolerance.
`SOLVER_ATOL`	float	`1e-10`	Absolute tolerance.
`SOLVER_NUM_POINTS`	int	`1000`	Number of evaluation points in the grid.

Solver Methods

Method	Description
`RK45`	Runge-Kutta 4(5) – general-purpose explicit method.
`RK23`	Runge-Kutta 2(3) – low-order, faster per step.
`DOP853`	Runge-Kutta 8(5,3) – high-order explicit method.
`Radau`	Implicit Runge-Kutta (Radau IIA) – stiff problems.
`BDF`	Backward Differentiation Formula – stiff problems.
`LSODA`	Adams/BDF auto-switching – stiff/non-stiff detection.

Logging & Update

Variable	Type	Default	Description
`LOG_LEVEL`	str	`INFO`	Verbosity: `DEBUG`, `INFO`, `WARNING`, `ERROR`, `CRITICAL`.
`LOG_FILE`	str	`differential_lab.log`	Log file name (project root).
`LOG_CONSOLE`	bool	`false`	Also print logs to the terminal.
`CHECK_UPDATES`	bool	`true`	Check for updates on startup (once per week).
`UPDATE_CHECK_INTERVAL_DAYS`	int	`7`	Days between automatic update checks.
`CHECK_UPDATES_FORCE`	bool	`false`	Force update check on every startup.
`UPDATE_CHECK_URL`	str	(main branch)	URL to pyproject.toml for version check.