Hi everybody,
I am trying to plot a function called 'r' defined as :
sage: var('r,alpha,beta')
sage: r = alpha/(alpha + beta)
whose components are:
sage: r_alpha = 1.0/(1.7 + e**(-(x+28.2)/13.5) )
sage: r_beta = e**(-(x+63.0)/7.8) / e**(-(x+28.8)/13.1+1.7)
However if I try now to plot r as as function of these equations, for
example as follows
sage: plot(r.subs(alpha = r_alpha, beta =r_beta),-100,100)
I get this error message:
sage: TypeError: reduce() or empty sequence with no initial value
Strange enough, I can plot both r_alpha and r_beta independently, and
resolve/plot the function numerically. Moreover, if I substitute
sage: r_alpha = 1.0/(1.7 + e**(-(x+28.2)/13.5) ) # remove numerator
sage : r_alpha = (1.7 + e**(-(x+28.2)/13.5) )
I can plot the function r (obviously this is not the desired function).
Does anybody has an idea about how to solve that?
--
José Guzmán
Physiologisches Institut der Universität Freiburg
Engesser Str. 4
Phone: +49-761-203-5165
Telefax: +49-761-203-5104
D-79108 Freiburg Germany
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