XDL Graphics Quick Reference

Available Demo Scripts

1. `plot_demo.xdl` - Simple 2D Plot

Basic sine wave demonstration.

xdl-gui examples/plot_demo.xdl

2. `plot_working_demo.xdl` - Comprehensive 2D Tests

Tests all 2D plotting features with 5 different plots.

xdl-gui examples/plot_working_demo.xdl

3. `plot3d_demo.xdl` - 3D Plotting Tests

Tests 3D data structures with SURFACE, CONTOUR, SHADE_SURF, and PLOT3D.

xdl examples/plot3d_demo.xdl

Quick Examples

2D Line Plot

x = FINDGEN(50) / 5.0
y = SIN(x)
PLOT, y, x

3D Surface Plot

z = [[1, 2, 3, 2, 1], [2, 4, 6, 4, 2], [3, 6, 9, 6, 3]]
SURFACE, z

Array Math

x = FINDGEN(10)
y = COS(x * 2.0)       ; Array multiplication and COS
z = EXP(-x)             ; Array negation and EXP
w = x + SIN(x)          ; Array addition

Supported Procedures

✅ Fully Working

PLOT - 2D line plots with GUI/PNG output
SURFACE - Parses 2D arrays for 3D surfaces
CONTOUR - Parses 2D arrays for contours
SHADE_SURF - Parses 2D arrays for shaded surfaces
PLOT3D - Parses 3 1D arrays for 3D lines

⚠️ Registered (Stubs)

See GRAPHICS_DEMOS_STATUS.md for complete list of 40+ registered procedures.

Supported Math Functions (with Array Support)

SIN, COS, TAN - Trigonometric functions
ASIN, ACOS, ATAN - Inverse trig functions
EXP - Exponential
SQRT - Square root
ABS - Absolute value
FINDGEN - Generate float arrays

Array Operations

Arithmetic

a = [1, 2, 3]
b = [4, 5, 6]
c = a + b        ; [5, 7, 9]
d = a * 2.0      ; [2, 4, 6]
e = a / 2.0      ; [0.5, 1.0, 1.5]

Unary

x = [1, 2, 3]
neg_x = -x       ; [-1, -2, -3]

Element-wise Functions

angles = FINDGEN(10) * 0.1
sines = SIN(angles)      ; Sin of each element
exps = EXP(-angles)      ; Exp of each negative element

Nested Arrays for 2D Data

; 3x3 matrix
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

; Access rows
row1 = matrix[0]         ; [1, 2, 3]

; Access elements
elem = matrix[1, 1]      ; 5

; Use in 3D plots
SURFACE, matrix

Common Patterns

Plotting Waves

t = FINDGEN(100) / 10.0
y = SIN(t)
PLOT, y, t

Exponential Decay

t = FINDGEN(50) / 5.0
y = EXP(-t)
PLOT, y, t

Combined Functions

x = FINDGEN(80) / 8.0
y = SIN(x) + COS(x * 2.0)
PLOT, y, x

3D Parametric Curves

t = FINDGEN(50) / 5.0
x = COS(t)
y = SIN(t)
z = t / 2.0
PLOT3D, x, y, z

Tips

GUI vs CLI: Use xdl-gui for interactive plots, xdl for PNG output
Array Size: Keep demo arrays small (< 100 elements) for quick testing
Nested Arrays: All rows must have same length for 2D data
Math Functions: All support both scalars and arrays
Negation: Use parentheses for clarity: y = EXP(-(x)) or y = EXP(-x)

Troubleshooting

“Unknown procedure: PLOT”

Make sure you’re running the correct binary:

# GUI mode
xdl-gui script.xdl

# CLI mode
xdl script.xdl

“Type mismatch” errors

Check that math functions are using correct types. All should work with arrays now.

“Expected a 2D nested array”

For SURFACE/CONTOUR/SHADE_SURF, use nested array literals:

z = [[1,2,3], [4,5,6], [7,8,9]]  ; Correct
z = FLTARR(3, 3)                  ; Not yet implemented