GDL/IDL to XDL Gap Analysis

Last Updated: 2025-12-30

This document identifies GDL/IDL functionality implementation status in XDL.

Summary

Category Implemented Pending Coverage
Core Functions 250+ ~50 ~83%
ML Functions 60+ ~10 ~86%
Graphics Procedures 50+ ~20 ~71%
Total 360+ ~80 ~82%

Completion: ~82% of common GDL/IDL functionality

Implementation Status by Category

1. Array Creation Functions ✅ COMPLETE

Function Status Notes
BYTARR ✅ Fully functional
INTARR ✅ Fully functional
LONARR ✅ Fully functional
FLTARR ✅ Fully functional
DBLARR ✅ Fully functional
STRARR ✅ Fully functional
COMPLEXARR ✅ Implemented
DCOMPLEXARR ✅ Implemented
MAKE_ARRAY ✅ With DIMENSION, VALUE, /INDEX keywords

2. Array Generation Functions ✅ COMPLETE

Function Status Notes
FINDGEN ✅ With START, INCREMENT keywords
INDGEN ✅ With START, INCREMENT keywords
DINDGEN ✅ Double precision
BINDGEN ✅ Byte generation
LINDGEN ✅ Long integer
L64INDGEN ✅ 64-bit integer
UINDGEN ✅ Unsigned
ULINDGEN ✅ Unsigned long
RANDOMU ✅ Uniform random
RANDOMN ✅ Gaussian random

3. Array Manipulation Functions ✅ COMPLETE

Function Status Notes
REFORM ✅ Reshape arrays
TRANSPOSE ✅ Matrix transpose
ROTATE ✅ Rotate arrays
SHIFT ✅ Shift elements
REBIN ✅ Resize by integer factors
CONGRID ✅ Resample/resize
REPLICATE ✅ Replicate values
ARRAY_INDICES ✅ Convert indices
ARRAY_EQUAL ✅ Compare arrays
UNIQ ✅ Find unique elements
HISTOGRAM ✅ Compute histogram
WHERE ✅ Full implementation
REVERSE ✅ Reverse order
SORT ✅ Sort elements
PERMUTE ✅ Permute dimensions
INTERPOL ✅ Linear interpolation
MESHGRID ✅ Coordinate matrices

4. Matrix/Linear Algebra Functions ✅ COMPLETE

Function Status Notes
IDENTITY ✅ Identity matrix
INVERT ✅ Matrix inversion
DETERM ✅ Determinant
TRACE ✅ Matrix trace
DIAGONAL ✅ Extract diagonal
CROSSP ✅ Cross product
DOTP ✅ Dot product
NORM ✅ Vector/matrix norm
SVDC ✅ SVD decomposition
LA_EIGENVAL ✅ Eigenvalues
LA_EIGENVEC ✅ Eigenvectors
LUDC ✅ LU decomposition
LUSOL ✅ LU solve
LA_LINEAR_EQUATION ✅ Solve Ax=b
LA_LEAST_SQUARES ✅ Least squares
LA_CHOLESKY ✅ Cholesky decomposition
LA_TRIDC ✅ Tridiagonal decomposition
QR ✅ QR decomposition
RANK ✅ Matrix rank
CRAMER ✅ Cramer’s rule
MATRIX_MULTIPLY ✅ Matrix multiplication
COND ✅ Condition number
PINV ✅ Pseudoinverse

5. Mathematical Functions ✅ COMPLETE

Function Status Notes
SIN, COS, TAN ✅ Trigonometric
ASIN, ACOS, ATAN, ATAN2 ✅ Inverse trig
SINH, COSH, TANH ✅ Hyperbolic
ASINH, ACOSH, ATANH ✅ Inverse hyperbolic
EXP, ALOG, ALOG10, ALOG2 ✅ Exponential/logarithmic
SQRT, ABS, POW ✅ Basic math
FLOOR, CEIL, ROUND ✅ Rounding
GAMMA, LNGAMMA ✅ Gamma function
ERF, ERFC ✅ Error function
BESSEL_J ✅ Bessel function
BETA ✅ Beta function
FACTORIAL ✅ Factorial
GCD, LCM ✅ Number theory
POLY ✅ Polynomial evaluation
BINOMIAL ✅ Binomial coefficient
PRIME, PRIMES ✅ Primality
PRODUCT ✅ Array product
DERIV ✅ Numerical derivative
INT_TABULATED ✅ Numerical integration
FINITE ✅ Test finite values
CHECK_MATH ✅ Check math errors
MACHAR ✅ Machine parameters

6. Statistics Functions ✅ COMPLETE

Function Status Notes
MIN, MAX, MEAN, TOTAL ✅ GPU-accelerated
VARIANCE, STDDEV ✅ GPU-accelerated
MEDIAN ✅ GPU-accelerated
MOMENT ✅ Statistical moments
MEANABSDEV ✅ Mean absolute deviation
SKEWNESS, KURTOSIS ✅ Distribution shape
CORRELATE ✅ Correlation coefficient
R_CORRELATE ✅ Spearman rank correlation
REGRESS ✅ Linear regression
LINFIT ✅ Linear least squares
POLY_FIT ✅ Polynomial fitting
CURVEFIT ✅ Levenberg-Marquardt
LADFIT ✅ L1 regression
SVDFIT ✅ SVD-based fitting
PERCENTILES ✅ Compute percentiles
ROBUST_MEAN ✅ Robust mean
TRIMMED_MEAN ✅ Trimmed mean
RESISTANT_MEAN ✅ Resistant mean
RANDOM_POISSON ✅ Poisson random
GAUSS_PDF ✅ Gaussian PDF
T_PDF ✅ Student’s t
CHISQR_PDF ✅ Chi-square

7. String Functions ✅ COMPLETE

Function Status Notes
STRLEN ✅ String length
STRPOS ✅ Find substring
STRMID ✅ Extract substring
STRUPCASE, STRLOWCASE ✅ Case conversion
STRTRIM ✅ Trim whitespace
STRJOIN ✅ Join strings
STRSPLIT ✅ Split strings
STRCMP ✅ Compare strings
STRCOMPRESS ✅ Compress whitespace
STRMATCH ✅ Wildcard matching
STRING ✅ Convert to string
STRREPLACE ✅ Replace substrings
STRPUT ✅ Insert substring
STRMESSAGE ✅ Error messages
STREGEX ✅ Regular expressions

8. File I/O Functions ✅ COMPLETE

Function Status Notes
GET_LUN, FREE_LUN ✅ LUN management
OPEN, OPENR, OPENW, OPENU ✅ File opening
CLOSE ✅ Close files
READF, READU ✅ Read operations
WRITEF, PRINTF, WRITEU ✅ Write operations
FLUSH ✅ Flush buffer
POINT_LUN ✅ Position pointer
EOF ✅ End of file test
ASSOC ✅ Associate file
FILE_BASENAME ✅ Extract filename
FILE_DIRNAME ✅ Extract directory
FILE_MKDIR ✅ Create directory
FILE_DELETE ✅ Delete files
FILE_COPY ✅ Copy files
FILE_MOVE ✅ Move files
FILE_TEST ✅ Test existence
FILE_LINES ✅ Count lines
FILE_INFO ✅ File metadata
FILE_EXPAND_PATH ✅ Expand path
FILE_SAME ✅ Compare paths
FILE_CHMOD ✅ Change permissions
FINDFILE ✅ Search files
FILEPATH ✅ Locate files

9. Image I/O Functions ✅ COMPLETE

Function Status Notes
READ_PNG, WRITE_PNG ✅ PNG format
READ_JPEG, WRITE_JPEG ✅ JPEG format
READ_TIFF, WRITE_TIFF ✅ TIFF format
READ_BMP, WRITE_BMP ✅ BMP format
READ_GIF, WRITE_GIF ✅ GIF format
READ_IMAGE, WRITE_IMAGE ✅ Auto-detect
QUERY_IMAGE ✅ Image dimensions
TV, TVSCL ✅ Display image

10. Signal Processing Functions ✅ COMPLETE

Function Status Notes
FFT ✅ 1D FFT (forward/inverse)
FFT_2D / FFT2 ✅ 2D FFT
A_CORRELATE ✅ Auto-correlation
C_CORRELATE ✅ Cross-correlation
SMOOTH ✅ Boxcar smoothing
CONVOL ✅ 1D/2D convolution
DIGITAL_FILTER ✅ Filter coefficients
HILBERT ✅ Hilbert transform
MEDIAN_FILTER ✅ Median filtering
BUTTERWORTH ✅ Butterworth filter
HANNING ✅ Hanning window
HAMMING ✅ Hamming window
BLACKMAN ✅ Blackman window
SAVGOL ✅ Savitzky-Golay
LEEFILT ✅ Lee filter
WV_HAAR ✅ Haar wavelet
WV_IHAAR ✅ Inverse Haar
WV_DWT ✅ Discrete wavelet
POWER_SPECTRUM ✅ Power spectral density

11. Image Processing Functions ✅ COMPLETE

Function Status Notes
SOBEL ✅ Sobel edge detection
ROBERTS ✅ Roberts cross
PREWITT ✅ Prewitt edge
CANNY ✅ Canny edge
LAPLACIAN ✅ Laplacian edge
EDGE_DOG ✅ Difference of Gaussians
DILATE ✅ Morphological dilation
ERODE ✅ Morphological erosion
MORPH_OPEN ✅ Morphological opening
MORPH_CLOSE ✅ Morphological closing
GAUSSIAN_FILTER ✅ Gaussian blur
THRESHOLD ✅ Binary thresholding
MEDIAN_2D ✅ 2D median filter
HIST_EQUAL ✅ Histogram equalization
HOUGH ✅ Hough transform
RADON ✅ Radon transform
WATERSHED ✅ Watershed segmentation
LABEL_REGION ✅ Connected components

12. Time & Date Functions ✅ COMPLETE

Function Status Notes
SYSTIME ✅ System time
JULDAY ✅ Julian day
CALDAT ✅ Calendar date
BIN_DATE ✅ Binary date/time
TIMESTAMP ✅ ISO 8601 timestamp
TIMEGEN ✅ Generate time array
DAYOFYEAR ✅ Day of year
JS2JD ✅ Julian seconds to date
WEEKDAY ✅ Day of week
TIC, TOC ✅ Timing functions

13. Type Conversion Functions ✅ COMPLETE

Function Status Notes
BYTE ✅ To byte
INT (FIX) ✅ To integer
LONG ✅ To long
FLOAT (FLT) ✅ To float
DOUBLE (DBL) ✅ To double
UINT ✅ Unsigned 16-bit
ULONG ✅ Unsigned 32-bit
LONG64 ✅ Signed 64-bit
ULONG64 ✅ Unsigned 64-bit
COMPLEX ✅ Complex number
DCOMPLEX ✅ Double complex

14. Pointer/Object Management ✅ COMPLETE

Function Status Notes
PTR_NEW ✅ Create pointer
PTR_VALID ✅ Check validity
PTR_FREE ✅ Free pointer
PTR_DEREF ✅ Dereference
OBJ_NEW ✅ Create object
OBJ_VALID ✅ Check validity
OBJ_DESTROY ✅ Destroy object
OBJ_CLASS ✅ Get class name
OBJ_ISA ✅ Check inheritance

15. Data Structures ✅ COMPLETE

Function Status Notes
SIZE ✅ Variable info
N_PARAMS ✅ Parameter count
TAG_NAMES ✅ Structure fields
N_TAGS ✅ Field count
HASH ✅ Hash table
LIST ✅ Create list
LIST_ADD ✅ Add to list
LIST_COUNT ✅ List length
ORDEREDHASH ✅ Ordered hash
DICTIONARY ✅ Dictionary
CREATE_STRUCT ✅ Create structure
STRUCT_ASSIGN ✅ Assign structure
HEAP_GC ✅ Garbage collection
HEAP_FREE ✅ Free heap

16. Complex Numbers ✅ COMPLETE

Function Status Notes
COMPLEX ✅ Create complex
DCOMPLEX ✅ Double complex
REAL ✅ Real part
IMAGINARY ✅ Imaginary part
CONJ ✅ Conjugate
ARG / PHASE ✅ Phase/argument
POLAR ✅ From polar
COMPLEX_EXP ✅ Complex exp
COMPLEX_LOG ✅ Complex log
COMPLEX_SQRT ✅ Complex sqrt
COMPLEX_SIN ✅ Complex sin
COMPLEX_COS ✅ Complex cos

17. System & Control ✅ COMPLETE

Function Status Notes
MESSAGE ✅ Print message
ON_ERROR ✅ Error handling
MEMORY ✅ Memory info
EXIT ✅ Exit session
STOP ✅ Halt execution
RETALL ✅ Return to top
ROUTINE_INFO ✅ Query routines
HELP ✅ Display help
CD ✅ Change directory
SPAWN ✅ Execute commands
WAIT ✅ Pause execution
EXECUTE ✅ Execute string
CONTINUE ✅ Continue loop
BREAK ✅ Break loop

Pending Features

Critical Priority

Feature Status Notes
User-defined procedures (PRO/ENDPRO) ❌ Pending Only top-level functions supported
GOTO statements ❌ Pending Label-based control flow
CASE/SWITCH statements ⚠️ Partial Tokens exist, limited implementation

High Priority

Feature Status Notes
FITS file I/O ❌ Pending Scientific data format
HDF5 file I/O ❌ Pending Scientific data format
NetCDF file I/O ❌ Pending Scientific data format
Widget/GUI system ⚠️ Partial Basic widgets exist

Medium Priority

Feature Status Notes
Map projections ❌ Pending MAP_SET, MAP_CONTINENTS
3D isosurface ❌ Pending ISOSURFACE
Volume rendering ❌ Pending SHADE_VOLUME
Particle tracing ❌ Pending PARTICLE_TRACE

Low Priority

Feature Status Notes
Database functions ⚠️ Partial MySQL, ODBC modules exist
Full object system ⚠️ Partial Basic OOP support
Advanced dialogs ❌ Pending DIALOG_* functions

GPU Acceleration Status

XDL includes GPU acceleration via xdl-amp with multiple backends:

Platform Backends Performance
macOS MLX, Metal, MPS, CoreML MLX: 1517x speedup for matmul
Windows DirectX12, DirectML, CUDA CUDA: Full support
Linux CUDA, ROCm, OpenCL CUDA: Full support

GPU-Accelerated Functions

  • MIN, MAX, MEAN, TOTAL (10-50x speedup)
  • MEDIAN, VARIANCE, STDDEV (SIMD-optimized)
  • Matrix multiplication via MLX (up to 1517x faster)

Platform Support

Platform Status Notes
macOS (Apple Silicon) ✅ Full MLX acceleration
macOS (Intel) ✅ Full Metal acceleration
Windows ✅ Full DirectX/CUDA
Linux ✅ Full CUDA/ROCm

Compatibility Features

MATLAB Support

  • MATLAB transpiler: 28/28 tests passing
  • ~80 MATLAB functions mapped to XDL
  • Direct .m file execution support

Python Integration

  • Python 3.13 support via PyO3
  • PYTHON_IMPORT, PYTHON_CALL, PYTHON_CALL_KW

Object-Oriented Syntax

  • Array methods: arr->Sum(), arr->Mean(), etc.
  • String methods: str->ToUpper(), str->Contains(), etc.
  • DataFrame methods: df->Head(), df->Column(), etc.

Conclusion

XDL has achieved ~82% coverage of common GDL/IDL functionality with:

  • ✅ 360+ functions implemented across all categories
  • ✅ GPU acceleration for performance-critical operations
  • ✅ Full linear algebra via nalgebra
  • ✅ Complete signal processing including FFT, wavelets
  • ✅ Image I/O and processing for all common formats
  • ✅ MATLAB compatibility layer
  • ✅ Python integration

Remaining gaps:

  • User-defined procedures (PRO/ENDPRO) - Critical
  • Scientific data formats (FITS, HDF5, NetCDF)
  • Advanced visualization (isosurfaces, volume rendering)
  • Widget/GUI system enhancements

References

  • IDL Documentation: https://www.l3harrisgeospatial.com/docs/routines.html
  • GDL Project: https://github.com/gnudatalanguage/gdl
  • XDL Implementation Status: IMPLEMENTATION_STATUS.md