bfathi

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8 years, 351 days

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These are questions asked by bfathi

hi friends

i have a problem in maple with an error

 restart:
 with(plots):with(linalg):
 r:=sqrt((xi-x)^2+y^2+z^2):
 sigma:=m/l:#linear mass density
 U:=Int(G*sigma/r,xi=-L/2..L/2);
 U:=normal(value(U));
 Us:=subs(G=1,m=1,L=1,z=1.5,U);
 plot3d(Us,x=-2..2,y=-2..2,axes=boxed,style=hidden,color=red,orientation=[-80,-130],numpoints=35^2,labels=['x','y','U']);

after this i see :

 Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct.

can you help me?

Thanks for your time

Best regards

hi friends

i have a problem in maple with an error

> Us:=subs(G=1,m=1,L=1,U):
> D2r:=[diff(x(t),t,t),diff(y(t),t,t),diff(z(t),t,t)]:
> g:=subs(x=x(t),y=y(t),z=z(t),grad(Us,[x,y,z])):
> IniC:=x(0)=1,D(x)(0)=0,y(0)=0,D(y)(0)=1,z(0)=3/4,D(z)(0)=0:
> Ns:=dsolve({seq(D2r[i]=g[i],i=1..3),IniC},{x(t),y(t),z(t)},numeric);

after this i see :

Error, (in f) unable to store 'grad(U, [1., 0., .750000000000000000])[1]' when datatype=float[8] 

meaning it can only store 8 byte hardware floats.
Is this statement true? And how can i solve this problem? Or could/should i use a different data type?

Thanks for your time

Best regards

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