Plot script reads from STDIN and specified file.

modsim/ass3/harm_osc.c

@@ -46,7 +46,7 @@ int f_lottka_volt(double t, double *y, double *dy, void *params) {
     // x' = -a * x + c * d * x * y
     dy[0] = - PARAM(0) * y[0] + PARAM(2) * PARAM(3) * y[0] * y[1];
     // y' = b * y - d * x * y
-    dy[1] = - PARAM(1) * y[1] - PARAM(3) * y[0] * y[1];
+    dy[1] = PARAM(1) * y[1] - PARAM(3) * y[0] * y[1];
     return 0;
 }
 

modsim/ass3/plot.py

 #!/usr/bin/env python
-from sys import argv, exit
+from sys import argv, exit, stdin
 from pylab import figure, clf, plot, show, savefig
 
-if len(argv) < 2:
-    print 'Usage: %s DATA_FILE [ TARGET_FILE ]' % argv[0]
-    exit()
-f = open(argv[1], 'r')
+try:
+    f = open(argv[1], 'r')
+except IndexError:
+    f = stdin
 lines = f.readlines()
 f.close()
 x = []