[gradsusr] Invalid Line coordinate

[Lyndon Mark Olaguera]

Hi all,
i would like to connect the 'eye' of a typhoon in grads. I extracted the
lat lon coordinates. I am using this script (below)..but i am encountering
an "invalid line coordinate" error.
Can anyone help me?
I attached the lat lon coordinates.

i=0
res=read('urbeye4.txt')
while(sublin(res,1)!=2)
  line = sublin(res,2)
  lat1=subwrd(res,3)
  lon1=subwrd(res,4)
 'q w2xy 'lon1' 'lat1
  xpos1 = subwrd(result,3)
  ypos1 = subwrd(result,6)
res=read('urbeye4.txt')
'draw wxsym 41 'xpos1' 'ypos1' 0.3 1'
if (i>0)
'set line 1 1 3'
'draw line 'xpos1' 'ypos1' 'xpos2' 'ypos2
endif
  xpos2=xpos1
  ypos2=ypos1
 i=i+1
endwhile


thanks,
bibokid
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ST  LAT    LON      TIME
1  19.9394  112.005 2011:9:25:0
1  17.801  132.444 2011:9:25:6
1  18.0683  129.406 2011:9:25:12
1  19.4048  129.13 2011:9:25:18
1  11.6531  130.234 2011:9:26:0
1  24.2162  119.463 2011:9:26:6
1  19.4048  128.025 2011:9:26:12
1  23.9489  119.186 2011:9:26:18
1  20.474  126.644 2011:9:27:0
1  7.3763  112.558 2011:9:27:6
1  21.8105  124.434 2011:9:27:12
1  22.0778  123.882 2011:9:27:18
1  11.3858  121.12 2011:9:28:0
1  10.5839  112.834 2011:9:28:6
1  16.4645  123.053 2011:9:28:12
1  22.6124  118.634 2011:9:28:18
1  21.2759  118.358 2011:9:29:0
1  18.6029  131.615 2011:9:29:6
1  18.3356  130.511 2011:9:29:12
1  19.1375  129.958 2011:9:29:18
1  18.8702  129.13 2011:9:30:0
ST  LAT    LON      TIME
ST  LAT    LON      TIME
1  19.9394  112.005 2011:9:27:0
1  17.801  132.444 2011:9:27:6
1  18.0683  129.406 2011:9:27:12
1  19.4048  129.13 2011:9:27:18
1  11.6531  130.234 2011:9:28:0
1  24.2162  119.463 2011:9:28:6
1  19.4048  128.025 2011:9:28:12
1  23.9489  119.186 2011:9:28:18
1  20.474  126.644 2011:9:29:0
1  7.3763  112.558 2011:9:29:6
1  21.8105  124.434 2011:9:29:12
1  22.0778  123.882 2011:9:29:18
1  11.3858  121.12 2011:9:30:0
1  10.5839  112.834 2011:9:30:6
1  16.4645  123.053 2011:9:30:12
1  22.6124  118.634 2011:9:30:18
1  21.2759  118.358 2011:10:1:0
1  18.6029  131.615 2011:10:1:6
1  18.3356  130.511 2011:10:1:12
1  19.1375  129.958 2011:10:1:18
1  18.8702  129.13 2011:10:2:0