Proposed list of canonical posts for the [matlab] tag wiki

matlab tag wiki canonicals.md

Proposed list of canonical posts for the [matlab] tag wiki on SO

• "Subscript indices must either be real positive integers or logicals" - Subscript indices must either be real positive integers or logicals, generic solution
• "Indexing in MATLAB" - Linear indexing, logical indexing, and all that
• "bsxfun vs repmat" - Comparing BSXFUN and REPMAT
• "Floating-point pitfalls" - Why is 24.0000 not equal to 24.0000 in MATLAB?
• "Dynamic variable names are bad and eval" - How to put these images together?
• "You can index the return value of a function, but you're probably not desperate enough" - How can I index a MATLAB array returned by a function without first assigning it to a local variable?
• "What are function handles?" - function handle in MATLAB
• "Are you sure you're using PCA correctly?" - PCA in matlab selecting top n components
• "How to visualize volumetric data?" - Reconstructing three dimensions image matlab
• "Remove duplicate rows from matrix" - How to remove duplicate rows from matrix ???

Please comment on additions and changes.

Possible subplot: https://stackoverflow.com/questions/26233064/plotting-multiple-graphs-in-a-single-window-by-using-matlab/26233197#26233197
I believe there must be a better one in SO

Here are some suggestions:

• How to call accumarray properly:
  http://stackoverflow.com/questions/17536558/fun-depending-on-order-of-subs-and-values-in-accumarray
  http://stackoverflow.com/questions/21689558/accumarray-makes-anomalous-calls-to-its-function-argument
• ' is not transpose (you were expecting this, weren't you)
  http://stackoverflow.com/q/25150027/2586922
• Shape agnostic slicing of arrays. The string ':' can be used as an index.
  http://stackoverflow.com/questions/22537326/on-shape-agnostic-slicing-of-ndarrays
• Matrix multiplication can beat bsxfun
  http://stackoverflow.com/questions/23911670/efficiently-compute-pairwise-squared-euclidean-distance-in-matlab
• Run-length decoding. Several methods and their performance.
  http://stackoverflow.com/questions/28501418/run-length-decoding-in-matlab
• Why timeit should be used rather than tic / toc
  http://stackoverflow.com/questions/18952552/timing-code-in-matlab
• Biggest integer that can be stored in a double
  http://stackoverflow.com/questions/1848700/biggest-integer-that-can-be-stored-in-a-double
• Finding islands of zeros in a sequence
  http://stackoverflow.com/questions/3274043/finding-islands-of-zeros-in-a-sequence

• Possibly this one about parfor :
  http://stackoverflow.com/questions/32146555/saving-time-and-memory-using-parfor-in-matlab/32146700#32146700
• Using i and j as variables (might be opinionated)
  http://stackoverflow.com/questions/14790740/using-i-and-j-as-variables-in-matlab
• Does using global variables impact performance?
  http://stackoverflow.com/questions/34450891/does-using-global-variables-impact-performance-in-matlab

(I was also including don't use Eval and don't do PCA if you don't know what you're doing, thanks for including them already.)

• "Debugging is your friend, more so when done intelligently"
  http://stackoverflow.com/questions/34027454/matlab-debugging-smarter-way-to-stop-the-code-with-an-specific-condition

• "Getting Inf or -Inf for results, look out for realmax"
  http://stackoverflow.com/questions/35971316/determinant-is-showing-infinity-instead-of-zero-why/35971682#35971682

Some answers:

• How to pass a struct array to another struct array?
  http://stackoverflow.com/questions/15133169/how-to-pass-a-struct-array-to-another-struct-array
• Vector as column index in matrix
  http://stackoverflow.com/questions/16508379/vector-as-column-index-in-matrix
• Replace all zeros in vector by previous non-zero value
  http://stackoverflow.com/questions/34041614/replace-all-zeros-in-vector-by-previous-non-zero-value
• How do I do multiple assignment in MATLAB?
  http://stackoverflow.com/questions/2337126/how-do-i-do-multiple-assignment-in-matlab
• Is it possible to define more than one function per file in MATLAB?
  http://stackoverflow.com/questions/3569933/is-it-possible-to-define-more-than-one-function-per-file-in-matlab
• MATLAB debugging: smarter way to stop the code with an specific condition?
  http://stackoverflow.com/questions/34027454/matlab-debugging-smarter-way-to-stop-the-code-with-an-specific-condition
• Inner matrix dimensions must agree?
  http://stackoverflow.com/questions/25778027/inner-matrix-dimensions-must-agree
• How can I find the maximum or minimum of a multi-dimensional matrix in MATLAB?
  http://stackoverflow.com/questions/2635120/how-can-i-find-the-maximum-or-minimum-of-a-multi-dimensional-matrix-in-matlab
• Swapping rows and columns
  http://stackoverflow.com/questions/4939738/swapping-rows-and-columns
• How to search for a string in cell array in MATLAB?
  http://stackoverflow.com/questions/8061344/how-to-search-for-a-string-in-cell-array-in-matlab
• Use a vector as an index to a matrix in MATLab
  http://stackoverflow.com/questions/5904488/use-a-vector-as-an-index-to-a-matrix-in-matlab
• MATLAB subplot margin
  http://stackoverflow.com/questions/4410873/matlab-subplot-margin
• Csvwrite with numbers larger than 7 digits
  http://stackoverflow.com/questions/14972147/csvwrite-with-numbers-larger-than-7-digits
• How to save a figure in MATLAB from the command line?
  http://stackoverflow.com/questions/12160184/how-to-save-a-figure-in-matlab-from-the-command-line
• plot inside a loop
  http://stackoverflow.com/questions/2800066/plot-inside-a-loop

Some useful QA, mainly dealing with performance:

• Is indexing vectors in MATLAB inefficient?
  http://stackoverflow.com/questions/13382155/is-indexing-vectors-in-matlab-inefficient
• How should I update the data of a plot in Matlab?
  http://stackoverflow.com/questions/13102654/how-should-i-update-the-data-of-a-plot-in-matlab
• Faster way to initialize arrays via empty matrix multiplication? (Matlab)
  http://stackoverflow.com/questions/14169222/faster-way-to-initialize-arrays-via-empty-matrix-multiplication-matlab
• How to initialize an array of structs in MATLAB?
  http://stackoverflow.com/questions/13664090/how-to-initialize-an-array-of-structs-in-matlab
• Is there a way in Matlab to determine the number of lines in a file without looping through each line?
  http://stackoverflow.com/questions/12176519/is-there-a-way-in-matlab-to-determine-the-number-of-lines-in-a-file-without-loop
• Fastest Matlab file reading?
  http://stackoverflow.com/questions/9440592/fastest-matlab-file-reading
• Why is MATLAB so fast in matrix multiplication?
  http://stackoverflow.com/questions/6058139/why-is-matlab-so-fast-in-matrix-multiplication

Some of my favourites:

• Dynamic Legend - Plot code in a loop and an entry into the legend is added at each iteration: http://stackoverflow.com/questions/21685911/dynamic-legend-updates-in-every-recursion/
• People complaining about the way MATLAB displays floating point numbers - Changing the display system from 1.4975e004 to 14975:
  http://stackoverflow.com/questions/1480177/how-do-i-go-from-1-4795e004-to-14795-00
• MATLAB does not support indexing into a sliced variable without assigning it to a temporary variable - http://stackoverflow.com/questions/3627107/how-can-i-index-a-matlab-array-returned-by-a-function-without-first-assigning-it
• Approaches to creating videos in MATLAB - http://stackoverflow.com/questions/11051307/approaches-to-create-a-video-in-matlab/
• How to smoothen a curve in MATLAB - http://stackoverflow.com/questions/1515977/how-to-smoothen-a-plot-in-matlab/
• How can I check the contents of a MAT file without loading it? - http://stackoverflow.com/questions/4026690/how-can-i-check-the-contents-of-a-mat-file-in-matlab-without-loading-it/
• Interpolation of scattered data, 2D array - http://stackoverflow.com/questions/16346684/how-to-perform-interpolation-on-a-2d-array-in-matlab

Don't press "run" to call a function -- MATLAB not enough input arguments

• In an assignment A(:) = B, the number of elements in A and B must be the same
  https://stackoverflow.com/questions/44563305/in-an-assignment-a-b-the-number-of-elements-in-a-and-b-must-be-the-same