ThU

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13 years, 62 days

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These are replies submitted by ThU

@cnheying 

it is just a warning, the solution is still there. You can suppress the warning with 

interface(warnlevel=0):

@Alejandro Jakubi 

unfortunately the typesetting details are not well documented. For instance, how can I increase the verical distance between x and y?

But now I have something to work with, thanks.

@nm

I was not aware of intsolve. Help pages says this command is just for linear integral equations, 

Hi,

The floats don't seem to be surprising, for small x you have sin(x)~x

So, sin(10^(-n-1/2)) is approximately 3.16227766/10^n

@rbdantas321 

how do you get x1 and x2 ?

@rbdantas321 

how do you get x1 and x2 ?

Carl, do you see a way to keep root point and tangent vector separate in the output? So that you really have <p>+t*<v> instead of <p+t*v>

 

 

Carl, do you see a way to keep root point and tangent vector separate in the output? So that you really have <p>+t*<v> instead of <p+t*v>

 

 

@gkokovidis

Here is the document mode more appealing. He just needs to know when he is allowed to drop multiplication signs...

 

 

@Mathematix 

 

restart; ode1 := L*(diff(i(t), t))+(R[1]+R[2])*i(t)+q(t)/C = 10*cos(8*t);

#now differentiate:

ode2 := diff(ode1, t);

ode2 := subs(diff(q(t), t) = i(t), ode2);

dsolve(eval({ode2, i(0) = 1, (D(i))(0) = 1}, [L = 4, R[1] = 8, R[2] = 6, C = 4]));

plot(rhs(%), t = 0 .. 2,y=0..1.2,gridlines=true);

 

solution has rationals and roots for coeffs, but should probably have integers. You may check the code.

@Mathematix 

 

restart; ode1 := L*(diff(i(t), t))+(R[1]+R[2])*i(t)+q(t)/C = 10*cos(8*t);

#now differentiate:

ode2 := diff(ode1, t);

ode2 := subs(diff(q(t), t) = i(t), ode2);

dsolve(eval({ode2, i(0) = 1, (D(i))(0) = 1}, [L = 4, R[1] = 8, R[2] = 6, C = 4]));

plot(rhs(%), t = 0 .. 2,y=0..1.2,gridlines=true);

 

solution has rationals and roots for coeffs, but should probably have integers. You may check the code.

Interesting mapping, kitonum.

Her another way. The task would be to compute the intersection points.

http://en.wikipedia.org/wiki/Shoelace_formula

 

 

Interesting mapping, kitonum.

Her another way. The task would be to compute the intersection points.

http://en.wikipedia.org/wiki/Shoelace_formula

 

 

@yhatagishi 

 

you could insert 
convert(simpledeq,rational); to remove the floats.

But the transform still ignores the given initial conditions. But more importantly, the  terms with square root are not transformed, I doubt there is an obvious way to do this.Even the direct way via dsolve yields no result, simpledeq is not so simple...

@yhatagishi 

 

you could insert 
convert(simpledeq,rational); to remove the floats.

But the transform still ignores the given initial conditions. But more importantly, the  terms with square root are not transformed, I doubt there is an obvious way to do this.Even the direct way via dsolve yields no result, simpledeq is not so simple...

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