...I want the equation to appear automatically on the graph and not I place each one.
Use text instead of gtext You'll have to use some pre-knowledge of what your curves look like to put it near the line where it doesn't interfere or pick a position known to be out of the way (like upper left or lower right).
xlab=some_x_position_in axes coordinates;
ylab=same_for_y;
text(x,y,num2str('y=%0.3f*x+%0.3f',p)
_ ...create a file which will save the constant term of each equation..._
Open the file before starting the loop and write each p(2) when it's been calculated.
fid=fopen('Yourdesiredfilename','wt');
for ...
...
fprintf(fid,'%f\n',p(2));
end
fid=fclose(fid);
