Computational Lab

The blackboard below can be pasted with the code to perform simple numerical calculations using numbers, vectors and matrices as elementary objects. Please see examples regarding the syntax and potential calculations. Any file to be used as part of the input can be uploaded using the button below. Any output file can be displayed by typing the file in the box e.g. "1.svg" but press the "Display Files" button to display it.

//csv extractor for CSV file from Tomo electrometer
//read csv file and look for tag =  time;

matrix A = csv_data("samples/Topographic_50mm.csv","time");
dvector columnList = column(0,4);

//get columns 0 to 4 in a matrix
matrix B = extractColumns(A,columnList);

//center based on average of 50 percent levels;
B= curveCenter2level(B,0.5);

//normalize curve at t=0 after centring;
B= curveNormalizeAt(B,0);

//generate scaling matrix;
//scaling 2x2 matrix: to scale x by 0.001 for ms->seconds. scale y by 100;
matrix scaler = column(0.001,0)|column(0,100);

B=B*scaler;

//now plot the curve in svg
svg S::size(1000,1100);
S::dimensions(2);
S::gStart("id='header' transform='translate(600,600) scale(5,-5) rotate(0)' ");

S::gStart("style='stroke: gray; stroke-width: 0.05; fill: none;'");
dvector x=column(-100,0,0);
dvector y=column(100,110,0);
S::grid_xy(x,y,5,5);
S::gEnd();

S::gStart("style='stroke: black; stroke-width: 0.08; fill: none;'");
S::line(column(0,0,0),column(0,110,0));
S::line(column(-100,0,0),column(100,0,0));
S::gEnd();

S::gStart("style='stroke: black; stroke-width: 0.05; fill: black; font-size: 2pt; font-family: Calibri;' text-anchor='middle'; transform='scale(1,-1)'");
S::gradedlineText(column(-100,0,0),column(100,0,0),column(-100,-50,0,50,100));
S::gradedlineText(column(0,0,0),column(0,-100,0),column(0,100));
S::gEnd();

//plot B in blue
S::gStart("style='stroke: blue; stroke-width: 0.3; fill: none;'");
S::graph(B);
S::gEnd();

S::gEnd();
S::write("1.svg");

Sample inputs
plot simple curve with two column x-y data
Plot data in single csv file in 1st and 4th column.
Analyze Topographic profile from Tomotherapy scans and plot difference (csv files)