Whenever I write [Octave] it means the stuff also works in Octave<\/p>\n
General<\/a> Entering long statements<\/strong> Output format [Octave]<\/strong> Variable type<\/strong> Difference between && and &<\/strong> Making new functions visible<\/strong> Syntax<\/strong> Number of arguments<\/strong> Variable number of input arguments<\/strong> Variable number of output arguments<\/strong> Anonymous functions<\/strong> Open a formatted text file<\/strong> Close file<\/strong> Filename<\/strong> fprintf tips<\/strong> Write (numeric) matrices to text file<\/strong> Read ASCII delimited numeric data file<\/strong> Read from file containing numbers and strings<\/strong> Read file containing numbers and NaN<\/strong> Delimiters (textscan and textread)<\/strong> Skipping fields (textscan and textread)<\/strong> Error message<\/strong> Debug a function that requires arguments<\/strong> Commands<\/strong> Measure time use<\/strong> Date formats<\/strong> Conversion functions<\/strong> Concatenate strings<\/strong> Plot with dates<\/strong> Subplots<\/strong> Double axis graphs<\/strong> Plot several data sets<\/strong> Grid<\/strong> Write text in the plot window<\/strong> Fix X and Y limits<\/strong> You have a non-uniform collection of measured points (from total station, differential gps, etc.) and you want to plot an interpolated surface. Whenever I write [Octave] it means the stuff also works in Octave General Functions I\/O Debug Dates and times Strings Plot Surface fitting General Entering long statements use ‘…’ all_data = textscan(fid, [‘%n %n.%n.%n-%n.%n %n %s %n %s %d %s %d’ … %s %d %s’]); Output format [Octave] format Most used options: short long rat: […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[],"class_list":["post-925","post","type-post","status-publish","format-standard","hentry","category-computer-stuff"],"jetpack-related-posts":[{"id":910,"url":"https:\/\/malemuk.com\/olofee\/emacs-tips\/","url_meta":{"origin":925,"position":0},"title":"Emacs tips","date":"December 31, 2015","format":false,"excerpt":"Essential shortcuts M-: META key (ALT on most keyboards) C-: CONTROL key C-x C-f : open file C-x b : switch to buffer C-x k : kill buffer C-s : search text forward C-r : search text backward C-+ \/ C-- : Zoom in\/out C-space: mark set (start of the\u2026","rel":"nofollow","context":"In \"Computer stuff\"","img":{"src":"","width":0,"height":0},"classes":[]},{"id":886,"url":"https:\/\/malemuk.com\/olofee\/coastal-sea-ice-action-on-a-breakwater-in-a-microtidal-inlet-in-svalbard-phd\/","url_meta":{"origin":925,"position":1},"title":"Coastal-sea-ice action on a breakwater in a microtidal inlet in Svalbard (PhD)","date":"December 31, 2015","format":false,"excerpt":"PhD Thesis (PDF) Abstract Preface LaTeX source code of the thesis Writing statistics Defence Trial lecture Defence video Defence slideshow Defence slideshow with notes Questions from the opponents Articles 19th IAHR International Symposium on Ice (2008) Caline, F. and Barrault, S., 2008, Transmission of level ice stresses to the ice\u2026","rel":"nofollow","context":"In \"PhD\"","img":{"src":"","width":0,"height":0},"classes":[]},{"id":137,"url":"https:\/\/malemuk.com\/olofee\/alpine-configuration\/","url_meta":{"origin":925,"position":2},"title":"Alpine configuration","date":"October 23, 2010","format":false,"excerpt":"Alpine is to email software what Emacs is to text-editing software. I love it. First, create a collection list -- I think you may skip this part if you're using pop instead of imap: S L A Nickname: any nickname Server: my.server.net:port\/ssl\/user=my_username If you're not using ssl, write tls instead.\u2026","rel":"nofollow","context":"In \"Computer stuff\"","img":{"src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/posts\/925","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/comments?post=925"}],"version-history":[{"count":7,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/posts\/925\/revisions"}],"predecessor-version":[{"id":955,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/posts\/925\/revisions\/955"}],"wp:attachment":[{"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/media?parent=925"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/categories?post=925"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/malemuk.com\/olofee\/wp-json\/wp\/v2\/tags?post=925"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nFunctions<\/a>
\nI\/O<\/a>
\nDebug<\/a>
\nDates and times<\/a>
\nStrings<\/a>
\nPlot<\/a>
\nSurface fitting<\/a><\/p>\nGeneral<\/h3>\n
\nuse ‘…’
\nall_data = textscan(fid, ['%n %n.%n.%n-%n.%n %n %s %n %s %d %s %d' ...
\n%s %d %s']);
\n<\/code><\/p>\n
\nformat<\/code>
\nMost used options:
\nshort<\/code>
\nlong<\/code>
\nrat:<\/code> ratio<\/p>\n
\nwhos myVar<\/code><\/p>\n
\n&& is a short-circuit version of the & logical operator meaning when entering
\na && b<\/code>
\nMatlab first evaluates a and if it is wrong, terminates immediately without evaluating b
\nExample:
\nif ( (x > 0) && (1\/x <3) ) % 1\/x will never be evaluated with x = 0<\/code><\/p>\nFunctions<\/h3>\n
\nIf you’re creating a new function with an editor that is not the Matlab editor, Matlab doesn’t detect it automatically. You solve this problem by typing
\nclear functions<\/code>
\nOf course the function file must be in your path, otherwise you can add it from the File menu<\/p>\n
\nfunction y = average(x)<\/code>
\n% AVERAGE Mean of vector elements.<\/code>
\n% only first comment line is printed when you type \"lookfor average\"<\/code>
\n% the other lines print when you type \"help average\"<\/code>
\ny = sum(x)\/length(x); % Actual computation<\/code><\/p>\nfunction [Xout,Yout] = myFunc(x)<\/code><\/p>\n
\nnargin: number of input arguments
\nnargout: number of output arguments<\/p>\n
\nfunction testvar(x1, x2, varargin)<\/code>
\nVarargin is a cell array. In the function body, access its cell values like this:
\nvarargin{i}(k)<\/code><\/p>\n
\nfunction [varargout] = testvar2(arrayin)<\/code>
\nVarargout is a cell array. Assign the cell values like this:
\nvarargout{i} = arrayin(k,:);<\/code><\/p>\n
\nDoes not require an M-file (perfect for defining functions in the command line)
\nf = @(arglist) expression<\/code>
\nexample:
\nsqr = @(x) x.^2;<\/code><\/p>\nI\/O<\/h3>\n
\nfid = fopen('file.dat','w')<\/code>
\nw<\/code>: write
\nr<\/code>: read
\na<\/code>: append
\nreturns -1 if error
\nIf the file is a text file and you want to write to it, consider using ‘t’ as an attribute if you want Windows line break
\nexample:
\nfid = fopen('file.txt', 'wt')<\/code><\/p>\n
\nfclose(fid)<\/code>
\nfclose('all') % closes all open files<\/code><\/p>\n
\n[pathstr, name, ext, versn] = fileparts(filein);<\/code>
\nfileout = fullfile(pathstr, [name, '.out']);<\/code>
\nWrite to formatted text file (line by line)
\nfprintf(fid,'%2.4f\\n',x)<\/code>
\nfid: 1 = stdout; 2 = stderr
\nomitting fid writes on the screen
\nd: integer
\nf: fixed point notation
\ne: exponential notation
\ng: same as f or e but insignificant zeros do not print
\ns: string of characters
\nc: character
\nRemember \\n for line break<\/p>\n
\nPrinting strings and numbers together: it looks like you have to separate the printing of strings and numbers into distinct fprintf statements. Example:
\nfprintf(fid, '%s', 'test ');<\/code>
\nfprintf(fid, '%d %d\\n', 10, 20); %printed on the same line as 'test <\/code>‘<\/p>\n
\nA = [1 2 3 4 ; 5 6 7 8];<\/code>
\ndlmwrite('my_data.out', A, ';')<\/code>
\n‘;’ is the delimiter in my_data.out
\n” means no delimiter
\nNote: not necessary to open the file first
\nNote: use the following notation if you want Windows line break:
\ndlmwrite('my_data.out', A, 'delimiter', ';', 'newline', 'pc')<\/code>
\nTo decide the number precision use the ‘precision’ attribute
\n'precision', '%10.5f<\/code>‘<\/p>\n
\ndata = dlmread('myfile.dat');<\/code>
\ncol1 = data(:,1);<\/code><\/p>\n
\ntextscan<\/code>
\nexample:
\nText file scan1.dat contains data in the following form:
\nSally Level1 12.34 45 1.23e10 inf NaN Yes<\/code>
\nJoe Level2 23.54 60 9e19 -inf 0.001 No<\/code>
\nBill Level3 34.90 12 2e5 10 100 No<\/code>
\nRead each column into a variable:
\nfid = fopen('scan1.dat');<\/code>
\nC = textscan(fid, '%s %s %f32 %d8 %u %f %f %s');<\/code>
\nfclose(fid);<\/code>
\nSpecifiers:
\n%s : string
\n%n : double
\n%d : int
\nNote that textscan returns a cell array. Therefore C{1} is the cell array containing the surnames ‘Sally’, ‘Joe’ and ‘Bill’. C{1}(1) is the cell containing the string ‘Sally’. To convert this cell to a string (i.e. a character array), use the char function:
\nsallyString = char(C{1}(1));<\/code>
\nThe conversion is necessary e.g. if you want to write out the string using fprintf<\/p>\n
\nexample:
\nnc = 6; % number of columns of data in the input file<\/code>
\nfmt = repmat('%n', 1, nc);<\/code>
\nclear m;<\/code>
\n[m{1:nc}] = textread(filein, fmt);<\/code>
\nm = cat(2,m{:});<\/code><\/p>\n
\nDefault delimiter:
\n' \\b\\t<\/code>‘
\nTo use a different delimiter:
\nC = textscan(fid, '%s %n', 'delimiter', '\\t');<\/code>
\nIf a nondefault delimiter is specified, repeated delimiter characters are treated as separate delimiters. When using the default delimiter, repeated white-space characters are treated as a single delimiter.<\/p>\n
\nUse asterisk: %*s instead of %s
\nParticularly handy when using textread where you can write the data directly into a list of variables<\/p>\n
\nerror('ERROR: wrong format');<\/code><\/p>\nDebug<\/h3>\n
\nOpen the function file in the editor
\nedit function.m<\/code>
\nRun the function from the command line
\nfunction(x,y)<\/code>
\nFor private functions:
\nedit private\/privFunc.m<\/code><\/p>\n
\ndisp(val): display values while debugging (or simply val)
\nreturn : continue execution
\ndbstep : execute current line
\ndbquit : exit debugging<\/p>\n
\ntic, toc: measure the time elapsed between invoking<\/p>\nDates and times<\/h3>\n
\nDate string: 24-Apr-2006
\nSerial date number: 732791
\nDate vector: 2006 04 24 0 0 0<\/p>\n
\ndatenum: convert to a serial date. In Octave 1 Jan 0000 is defined as day 1.
\ndatestr: convert to string representation of the date
\ndatevec: convert to a date vector
\nExample: the 265th day of year 2007 is
\ndatestr(datenum(2007,01,01) + 264)<\/code><\/p>\nStrings<\/h3>\n
\nnewString = [string1, string2, string3];<\/code>
\nConvert an integer to a string
\nnewString = int2str(n);<\/code><\/p>\nPlot<\/h3>\n
\nExample:
\nplot(dates, y);<\/code>
\ndatetick('x', 19);<\/code>
\nNote1: dates must be a vector of serial dates (obtained with datenum)
\nNote2: 19 is one of a series of different formats that datetick can print the date into.
\nNote3: you might want to add ‘keepticks’ as a third input argument in order to get a good tick repartition.<\/p>\n
\nYou can plot several plots in the same window with the subplot command.
\nExample – drawing two plots next to each other:
\nsubplot(1,2,1);<\/code>
\nplot(x1,y1);<\/code>
\nsubplot(1,2,2);<\/code>
\nplot(x2,y2);<\/code>
\nThe two first figures indicate how the window is split, here 1 row and 2 columns while the third figure is the subwindow index.<\/p>\n
\nIn order to plot y1=f(x1) and y2=g(x2) with two Y-axes, copy the following lines:
\nline(x1,y1,'Color','r');<\/code>
\nax1 = gca;<\/code>
\nset(ax1,'XColor','r','YColor','r')<\/code>
\nax2 = axes( 'Position',get(ax1,'Position'),. . . <\/code>
\n 'XAxisLocation','top',. . . <\/code>
\n 'YAxisLocation','right',. . . <\/code>
\n 'Color','none',. . . <\/code>
\n 'XColor','k','YColor','k'); <\/code>
\nline(x2,y2,'Color','k','Parent',ax2);<\/code><\/p>\n
\nEach time you call the plot<\/code> command, it clears the plot window. If you want to keep the previous plot, you need to write
\nhold all<\/code>
\nbefore the first plot<\/code> command and
\nRemember to write
\nhold off<\/code>
\nafter the last plot<\/code> command. That way, the plot window will behave “normally” on the next plot<\/code> call.<\/p>\n
\nExamples:
\nset(gca, 'XGrid', 'on')<\/code>
\nset(gca, 'XMinorGrid', 'off')<\/code><\/p>\n
\nThe easiest way is to use the text<\/code> command:
\ntext(xpos, ypos, str)<\/code>
\nCheck also out the annotations<\/code> command<\/p>\n
\nxlim([xmin xmax])<\/code>
\nylim([ymin ymax])<\/code><\/p>\nSurface fitting<\/h3>\n
\nSuppose your points are stored as X, Y, Z.
\nFirst you build a uniform grid based on the extremities of the measured area:
\n[Xm, Ym] = meshgrid (Xmin:s:Xmax, Ymin:s:Ymax);<\/code>
\nwhere s is the grid size
\nThen you interpolate the surface at all the grid points:
\nZm = griddata (X, Y, Z, Xm, Ym);<\/code>
\nEventually you may plot the surface:
\nsurf(Zi)<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"