I looked at your problem. A few observations.
On 27 mei, 18:13, rpoirier <rpoir...@champlaincollege.qc.ca> wrote:
> I want to solve a relativity problem using SOLVE.
> I used to be able to, but now I run into a problem.
>
> lp=60e9*1000
> dtp=1.25*24*3600
> beta=var('beta')
> gamma=1/(sqrt(1-beta^2))
> solve(dtp*gamma==lp/(beta*c),beta)
1) The variable c is not defined. In general, when you ask a
question, please ensure it is complete.
> the result I expect is a numerical value, but I get the following:
> [beta == 733841/396000*sqrt(-beta^2 + 1)]
>From the answer, I found as value: c=396000*60e9*1000/
(1.25*24*3600*733841)
2) 'beta' is a variable, and mathematically it could be many things.
For instance a matrix....
So the solution is correct, and to get a numeric value you could use a
more specific function.
Via plot(dtp*gamma-lp/(beta*c),0,1) we see that 0.7 is near the
numerical solution.
Now apply a routine specifically for finding numerical solutions:
find_root(dtp*gamma-lp/(beta*c),0.5,0.9)
0.88004280932699031
3) But your problem has an interesting aspect, and it raises a
question for me.
Both lp and c are both reals: <type
'sage.rings.real_mpfr.RealNumber'>. But the solution yields
733841/396000, a rational number (<type
'sage.rings.rational.Rational'>). Why?
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