This looks like a bug. Aaron Meurer
On Thu, Dec 19, 2013 at 5:16 PM, eTna <[email protected]> wrote: > Hi, > > Trying to write something with sympy for the first time... I'm stuck with > some error and not to sure which way to look. The code is fairly short: I > define a profit function, a cdf, and would like to compute the expected > profit for a range of prices, depending on some parameter's value: > > s_theta, s_p, s_p_bar, s_eta, s_gamma = symbols('s_theta s_p s_p_bar s_eta > s_gamma') > > class function_profit(Function): > nargs = 4 > > @classmethod > def eval(cls, s_theta, s_p, s_p_bar, s_eta): > return Piecewise((0, s_p > s_p_bar), ((s_p - 0.1)*(s_theta + > s_p**(-s_eta)), True)) > > class function_cdf_theta(Function): > nargs = 2 > > @classmethod > def eval(cls, s_theta, s_gamma): > return Piecewise((0, s_theta < 0), (1, s_theta > 1), (s_theta**s_gamma, > True)) > > class function_expected_profit(Function): > nargs = 4 > > @classmethod > def eval(cls, s_p, s_p_bar, s_eta, s_gamma): > return integrate(function_profit(s_theta, s_p, s_p_bar, s_eta)*\ > diff(function_cdf_theta(s_theta, s_gamma), s_theta), > (s_theta, 0, 1)) > > for gamma in [0.5, 0.7, 1.0]: > x_axis = np.linspace(0.1, 2.0, int(round(((2.0-0.1)/0.1)))+1) > ls_profits = [function_expected_profit(x, 2.0, 2.0, gamma) for x in > x_axis] > plt.plot(x_axis, ls_profits, label = 'gamma = %s' %gamma) > legend = plt.legend(loc='upper right') > plt.show() > > The profit and cdf functions seem to work fine, the differentiation of the > cdf as well... but I can compute the expected profit only for gamma = 1. > Trying to compute the expected profit with gamma = 0.5, I get "ValueError: > Non-suitable parameters.". > > Many thanks for your time and sorry about the noobish question, > > Etienne > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
