Thanks to all.
I don't know whether this rises to general interest,
but I think so.
How this arose.
I was noodling around and asked for
integrate(sin(x^2),x);
I got back some interesting form in terms of erf
(as an alternative to the usual textbook form).
This checked out OK on differentiation.
However, it wouldn't plot, and wouldn't evaluate for x=1.
Using rectform or ev(...,numer) doesn't seem to help.
The problem seems already present in erf(%i)
Thanks again,
Seth Goldberg
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