ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 07 Apr 2021 14:49:01 +0200Maxima wants to know whether %k1 is positive or negativehttps://ask.sagemath.org/question/56526/maxima-wants-to-know-whether-k1-is-positive-or-negative/Trying to solve a differential equation in Sage:
sage: de = -diff(y, x, 2) - G*M/y^2
sage: desolve(de, y, ics=[0, 1000])
I get a type error and a question:
TypeError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(%k1>0)', see `assume?` for more details)
Is %k1 positive or negative?
But when I use `assume(%k1>0)` I get a syntax error,
saying that there's something wrong with the percent sign.Dr. BananaWed, 07 Apr 2021 14:49:01 +0200https://ask.sagemath.org/question/56526/Why doesn't assume(x, 'real') exclude complex values when using plot(x^(1/3)) over a negative domain?https://ask.sagemath.org/question/44798/why-doesnt-assumex-real-exclude-complex-values-when-using-plotx13-over-a-negative-domain/ Running the following commands:
assume(x,'real')
plot(x^(1/3), -5, 5)
produces the following error:
verbose 0 (3630: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 100 points.
verbose 0 (3630: plot.py, generate_plot_points) Last error message: 'negative number cannot be raised to a fractional power'
Shouldn't the assume command take care of this?
Thanks.
douglas.y.youngFri, 28 Dec 2018 04:04:18 +0100https://ask.sagemath.org/question/44798/