Create a "file.dat" from the windows CMD - c++

Question

When running the following C ++ script I obtain the necessary data to work in Gnuplot.
#include "stdio.h"
double TT;/* Imaginary part of T matrix */
double x;/* Real part of Energy */
double y;/* Imaginary part of Energy */
double G;/*Resonance Peak width */
double ER;/* Resonance Peak Energy */
main()
{
G = 120.;
ER=180.;
for(x=150.;x<=200.;x=x+1.){
for(y=-70.;y<=-50.;y=y+0.5){
/* Plotting T as a function of x and y */
TT = (G/2.)*(y+(G/2.))/(ER*ER - 2.*ER*x + G*y + (G*G/4.) + x*x + y*y);
printf("%g %2.1f %f\n", x,y,TT); /*Printing out T to standard output*/
}
printf("\n"); /* printing a newline after every column(this part is crutial) */
}
}
from the command Prompt I run the following command line:
.\3D_Data start notepad++ > mytextfile.dat
When calling the point DAT file in Gnuplot
I get the following Alert:
gnuplot> splot 'mytextfile.dat'
warning: Bad data on line 1 of file mytextfile.dat
Not enough input columns
If the content of the file is copied and inserted into a new file within Notepad ++ and saved with extension Dat; then it runs correctly in Gnuplot
I have tried with these command lines without any results
// C:\projects\helloworld> .\3D_Data ./a.out > 3Ddata
// PS C:\projects\helloworld> .\3D_Data > result.txt
// PS C:\projects\helloworld> .\3D_Data | Out-File -FilePath .\OUTPUT.txt
// PS C:\projects\helloworld> .\3D_Data test.exe > myoutput.txt
// PS C:\projects\helloworld> .\3D_Data copy > SN.txt
// PS C:\projects\helloworld> .\3D_Data echo > filename2.txt
// C:\projects\helloworld> .\3D_Data /S > Myfile.dat
something I have noticed is that the file created from Notepad ++ is almost twice small in size.
Is it possible to get a file from the CMD that is accepted by Gnuplot functions?
G N U P L O T
Version 5.4 patchlevel 1 last modified 2020-12-01

Answer 1

Well, the code you use looks more like C and not C++.
(which is fine too)
In C, you can use fprinf instead of printf .. have a look here:
#include <stdio.h>
int main () {
FILE *file;
const double G = 120.;
const double ER=180.;
file = fopen("file.dat","w+");//create or overwrites a file
for(int x=150; x<=200; x++){
for(double y=-70.; y<=-50.; y += 0.5){
TT = (G/2.)*(y+(G/2.))/(ER*ER - 2.*ER*x + G*y + (G*G/4.) + x*x + y*y);
fprintf(file,"%g %2.1f %f\n", x, y, TT); //writes into a file
}
fprintf(file,"\n");//same here
}
fclose(file);//flushes the file and closes it
return(0);
}
In C++, you can use fstream instead of printf .. have a look here:
#include <fstream>
#include <format>
int main () {
std::ofstream file("file.dat", std::ofstream::out | std::ofstream::trunc);
const double G = 120.;
const double ER = 180.;
for(int x=150; x<=200; x++){
for(double y=-70.; y<=-50.; y += 0.5){
TT = (G/2.)*(y+(G/2.))/(ER*ER - 2.*ER*x + G*y + (G*G/4.) + x*x + y*y);
file << x << " " << std::format("{:2.1f}",y) << TT << "\n"; //writes into a file // EDIT: I added the C++20 std::format
}
file << std::endl;//same here
}
file.close();//flushes the file and closes it
return(0);
}
Some tipps:
Ty to fix all warnings (you should have had some)
Try to do proper spaces and indentations!
make variable names readable
try to make source code that a human can read (without comments if possible)
try to make functions that express your calculations
EDIT: I changed the command int the C++ example to std::format(..), as I had an error in the code.

Answer 2

TT(x,y) = (G / 2.) * (y + (G / 2.)) / (ER * ER - 2. * ER * x + G * y + (G * G / 4.) + x * x + y * y)
ER=180.
G = 120.
set table 'test3D.dat'
splot [150:200] [-70:-50.1] TT(x,y)
unset table
splot 'test3D.dat' with lines