2021-10-25 22:43:57 +0100 received badge ● Popular Question (source) 2019-01-03 21:04:34 +0100 commented question TypeError 'unable to simplify to float approximation' while trying to define an integral operator I still get an error, I defined K as K(x,y,t)=1/(x^2+y^2+t^2+1)  How can I define them as formal variables? 2018-12-30 00:55:39 +0100 asked a question TypeError 'unable to simplify to float approximation' while trying to define an integral operator Hello, I am trying to define an integral operator acting on a subspace of $L^2(\mathbb{R})$ that depends of time using sage. Being more explicit $W(t)$ takes a real function $f$ and returns another function $g$ defined by \begin{equation} W(t)f(x)=g(x)=\int_{-\infty}^{+\infty}K(x,y,z)f(y)\text{d}y \end{equation} This is the code I came up with def W(t): def dummy2(f): def dummy3(x): integrand(y)=f(y)*K(x,y,t) return numerical_integral(integrand,-Infinity,+Infinity,algorithm='qag') return dummy3 return dummy2  With $K$ a reasonable function of $x,y,t$ However I am getting the following error TypeError: unable to simplify to float approximation  I am pretty sure it's related to the types passed to numerical_integrand What could be a solution? Or a better way to implement it? Thank you all