2021-10-27 15:10:58 +0200 received badge ● Famous Question (source) 2016-02-15 11:14:01 +0200 received badge ● Notable Question (source) 2015-06-04 17:51:01 +0200 received badge ● Popular Question (source) 2014-01-20 10:10:51 +0200 received badge ● Student (source) 2014-01-19 06:33:02 +0200 commented question Numeric evaluation of exp(x^2) in a sum TypeError Interestingly, calling n on the symbolic answer works: sage: n(sum(e^(i^2), i, -1, 1)) 6.43656365691809 2014-01-19 06:29:40 +0200 asked a question Numeric evaluation of exp(x^2) in a sum TypeError Define simple function of one variable with sum: sage: r, i = var('r i') sage: h(r) = sum(exp(i), i, -r, r) sage: n(h(1)) 4.08616126963049  OK, now change the argument of exponent to i^2: sage: h(r) = sum(exp(i^2), i, -r, r) sage: n(h(1)) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) in () ----> 1 n(h(Integer(1))) /usr/lib/sagemath/local/lib/python2.7/site-packages/sage/misc/functional.pyc in numerical_approx(x, prec, digits) 1395 prec = int((digits+1) * LOG_TEN_TWO_PLUS_EPSILON) + 1 1396 try: -> 1397 return x._numerical_approx(prec) 1398 except AttributeError: 1399 from sage.rings.complex_double import is_ComplexDoubleElement /usr/lib/sagemath/local/lib/python2.7/site-packages/sage/symbolic/expression.so in sage.symbolic.expression.Expression._numerical_approx (sage/symbolic/expression.cpp:22617)() TypeError: cannot evaluate symbolic expression numerically  Why is that and what am I doing wrong?