Topic: bug in relations + derivative request

Ivan,
In the beta version, the relation (x+y)^2<=x^2+2*x*y+y^2 causes graph to crash.  Of course the given relation is true period.

Why not be able to differentiate the function integrate?  "Usually", the integrand g is continuous and so for example integrate(g(s),s,0,x) has derivative g.  Similarly for differentiable functions as limits of integration and also when the integrand is a function of both s and x.  Aside, if the integrand is not continuous, the integrate function may well be wrong anyway; for example the graph of integrate(floor(s),s,0,x) is clearly wrong.

Re: bug in relations + derivative request

Unfortunately it looks like a bug in Window that is not easy work around, but I will try to see what I can do about it.

Why do you want to differentiate the integrate function? The reason Graph does not support it is that it is a little difficult to do in a generic way, i.e. how do you differentiate integrate(g(s), s, -x^2, sin(x)).

Re: bug in relations + derivative request

As one use, it seems to me that one should be able to draw tangent lines for a graph involving integrate.
Assuming relatively mild conditions on the functions involved, of course the derivative of integrate(g(s,x),s,u(x),v(x)) is integrate(g2(s,x),s,u(x),v(x))+g(v(x),x)*v'(x)-g(u(x),x)*u'(x).  I don't know how you've implemented derivatives, but this shouldn't be too much of an extension.

Re: bug in relations + derivative request

You are of course right. I did not investigate that very well. It is the most difficult function to differentiate but I will try to get it implemented. It should be possible.

Re: bug in relations + derivative request

I have now implemented support for differentiating the integrate function. You can find it in the latest beta version (build 499). Let me know how it works.

Re: bug in relations + derivative request

Ivan,
Thanks for the rapid response.  I tested the derivative of several integrate functions and also drew several tangent lines.  It all looks good.  Of course, as always there could be hidden bugs lurking, but I doubt it.
JohnG