formula.py handle imaginary correctly; symmath_check add numerical option

lms/lib/symmath/formula.py

@@ -409,8 +409,7 @@ class formula(object):
                 if 'hat' in usym:
                     sym = my_sympify(usym)
                 else:
-                    if usym == 'i': print "options=", self.options
-                    if usym == 'i' and 'imaginary' in self.options:	 # i = sqrt(-1)
+                    if usym == 'i' and self.options is not None and 'imaginary' in self.options:	 # i = sqrt(-1)
                         sym = sympy.I
                     else:
                         sym = sympy.Symbol(str(usym))

lms/lib/symmath/symmath_check.py

@@ -175,6 +175,7 @@ def symmath_check(expect, ans, dynamath=None, options=None, debug=None, xml=None
     do_matrix = 'matrix' in (options or '')
     do_qubit = 'qubit' in (options or '')
     do_imaginary = 'imaginary' in (options or '')
+    do_numerical = 'numerical' in (options or '')
 
     # parse expected answer
     try:
@@ -196,6 +197,13 @@ def symmath_check(expect, ans, dynamath=None, options=None, debug=None, xml=None
             msg += '<p>You entered: %s</p>' % to_latex(fans)
             return {'ok': False, 'msg': msg}
 
+    if do_numerical:		# numerical answer expected - force numerical comparison
+        if abs(abs(fans - fexpect) / fexpect) < threshold:
+            return {'ok': True, 'msg': msg}
+        else:
+            msg += '<p>You entered: %s (note that a numerical answer is expected)</p>' % to_latex(fans)
+            return {'ok': False, 'msg': msg}
+
     if fexpect == fans:
         msg += '<p>You entered: %s</p>' % to_latex(fans)
         return {'ok': True, 'msg': msg}