粒子の位置を出力する (2次元)
call cg_iric_write_sol_particlegroup_pos2d(fid, x, y, ier)
ier = cg_iRIC_Write_Sol_ParticleGroup_Pos2d(fid, x, y);
cg_iRIC_Write_Sol_ParticleGroup_Pos2d(fid, x, y)