UNIX for Advanced & Expert Users

$ program_that_spews_gigs_of_data | gzip > data.gz
# Tell the gnuplot script to process "/dev/stdin" or "/proc/self/fd/0" instead
# of a filename
$ gunzip < data.gz | gnuplot file.script

$ gnuplot
> help plot
...
Subtopics available for plot:
    acsplines         axes              bezier            binary
    csplines          cumulative        datafile          errorbars
    errorlines        every             example           frequency
    index             iteration         kdensity          matrix
    parametric        ranges            sbezier           smooth
    special-filenames style             thru              title
    unique            using             with

Subtopic of plot: binary

 The `binary` keyword allows a data file to be binary as opposed to ASCII.
 There are two formats for binary--matrix binary and general binary.  Matrix
 binary is a fixed format in which data appears in a 2D array with an extra
 row and column for coordinate values.  General binary is a flexible format
 for which details about the file must be given at the command line.

 See `binary matrix` or `binary general` for more details.

Subtopics available for plot binary:
    general           matrix

Subtopic of plot binary: matrix

 Gnuplot can read matrix binary files by use of the option `binary` appearing
 without keyword qualifications unique to general binary, i.e., `array`,
 `record`, `format`, or `filetype`.  Other general binary keywords for
 translation should also apply to matrix binary.  (See `binary general` for
 more details.)

 In previous versions, `gnuplot` dynamically detected binary data files.  It
 is now necessary to specify the keyword `binary` directly after the filename.

 Single precision floats are stored in a binary file as follows:

       <N+1>  <y0>   <y1>   <y2>  ...  <yN>
        <x0> <z0,0> <z0,1> <z0,2> ... <z0,N>
        <x1> <z1,0> <z1,1> <z1,2> ... <z1,N>
         :      :      :      :   ...    :
...

{
        double close_enough=3.14;
        FILE *fout=fopen("filename", "w");
        write(&close_enough, 1, sizeof(close_enough), fout);
        fclose(fout);
}

double close_enough=3.14;
        FILE *fout=fopen("filename", "w");
        write(&close_enough, 1, sizeof(close_enough), fout);
        fclose(fout);

sprintf(buffer, "%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\t%lg\n", 
							fluence, t, x, z, Te(i,j), 
							Ti(i,j), eDensity(i,j), hDensity(i,j), Intensity(i), intensity(i,j), 
							H(i,j), phase(i,j), angleIncidence, angleRefracted(i,j));
						fwrite(buffer, 1, sizeof(buffer), MainOutput);

// Generate a raw binary file for gnuplot to work with.
// compile with -lm

#include <stdio.h>
#include <math.h>

int main(void)
{
        int n, points=100;
        FILE *fp=fopen("sin.bin", "wb");

        for(n=0; n<points; n++)
        {
                float v[3]= { (2*3.14159*n)/(points-1) };
                v[1]=sin(v[0]);         v[2]=cos(v[0]);
                // writes three floats in a row.  x, sin(x), cos(x)
                fwrite(v, 3, sizeof(float), fp);
        }
        fclose(fp);
        return(0);
}

$ gcc graph.c -lm
$ ./a.out
$ ls -l sin.bin
-rw-r--r-- 1 monttyle monttyle 1200 Mar 23 18:15 sin.bin
$ gnuplot
> plot "sin.bin" binary format='%f%f%f' using 1:2;
(pops up a picture of a sine wave)
>

double buffer[]={x, y, Z(i,j)}; 
fwrite(buffer, sizeof(double), sizeof(buffer), Mesh);

gnuplot> plot "Mesh0.dat" binary format='%3lf' using 2:3 w d

gnuplot> plot "< awk '{if($1==0) print }' Mesh0.dat" using 2:3 with dots