title: Contour plot in Xmgrace
body: <p><img src="https://i.stack.imgur.com/bjO8F.jpg" alt="enter image description here">I have a data file containing 3 columns. Now I want to have a contour plot with xmgrace as I use xmgrace mostly. But somehow, I am unable to do draw it now. Can anyone help me a bit? Thanks in advance.
  The data is in format shown below:</p>
  
  <p>3.24 4.78 0.015776
  3.24 4.80 0.011777
  3.24 4.82 0.00986
  3.24 4.84 0.010185
  3.24 4.86 0.012515
  3.26 4.78 0.009244
  3.26 4.80 0.006368
  3.26 4.82 0.005792
  3.26 4.84 0.007121
  3.26 4.86 0.010361
  3.28 4.78 0.004666
  3.28 4.80 0.0028
  3.28 4.82 0.003017
  3.28 4.84 0.005285
  3.28 4.86 0.0095
  3.30 4.78 0.001295
  3.30 4.80 0.000557
  3.30 4.82 0.001924
  3.30 4.84 0.005266
  3.30 4.86 0.010401
  3.32 4.78 0
  3.32 4.80 0.000233
  3.32 4.82 0.002508
  3.32 4.84 0.006666
  3.32 4.86 0.012515
  3.34 4.70 0.012943
  3.34 4.72 0.006904
  3.34 4.74 0.002791
  3.34 4.76 0.000662
  3.36 4.70 0.011024
  3.36 4.72 0.005998
  3.36 4.74 0.003063
  3.36 4.76 0.001814
  3.38 4.70 0.011203
  3.38 4.72 0.007077
  3.38 4.74 0.004755
  3.38 4.76 0.004188
  3.40 4.70 0.01263
  3.40 4.72 0.009182
  3.40 4.74 0.007685
  3.40 4.76 0.007985</p>
  
  <p>The final curve should be like as shown in the attachment.</p>