Markiyan Hirnyk

Markiyan Hirnyk

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12 years, 58 days

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These are questions asked by Markiyan Hirnyk

of the matrix

Matrix(n, (i, j) ->binomial(a*i+b*j, j) );

? I mean an explicit formula in terms of a, b, and n which consists of n+1 summands. Of course, it should be found with Maple, not by hand.

restart; CodeTools:-Usage(plots:-inequal({abs(abs(x-y)-abs(x+y)) >= 2*y-x+1, (x+1)^2+(y+1)^2 <= 2}, 
optionsimplicit = [gridrefine = 2, rational = true], x = -3 .. 1, y = -3 .. 0., scaling = constrained));

memory used=0.57GiB, alloc change=184.01MiB, cpu time=16.22s, real time=17.24s, gc time=1.58s

?

Mathematica 11.2.0.0 says

113053/146523-8/169 sqrt(22)+32/289 sqrt(30)-3/169 sqrt(214-24 sqrt(22))-
2/169 sqrt(1177-132 sqrt(22))-1/289 sqrt(94-16 sqrt(30))-
4/289 sqrt(705-120 sqrt(30))+1/146523 293046(Pi)-
arcsin(1/13 sqrt(2) (3+sqrt(22)))-arcsin(1/17 sqrt(2) (1+2 sqrt(30)))

(see Area.pdf).

Namely, I mean

solve({y >= 4*x^4+4*x^2*y+1/2, sqrt((1/2)*(x-y)^2-(x-y)^4) = -2*x^2+y^2}, [x, y]);
                               []

The answer (no solution) is not correct in view of 

eval({y >= 4*x^4+4*x^2*y+1/2, sqrt((1/2)*(x-y)^2-(x-y)^4) = -2*x^2+y^2}, [x = 0, y = 1/2]);
      {(1/8)*sqrt(4) = 1/4, 1/2 <= 1/2}
eval({y >= 4*x^4+4*x^2*y+1/2, sqrt((1/2)*(x-y)^2-(x-y)^4) = -2*x^2+y^2}, [x = -1, y = -3/2]);
      {(1/8)*sqrt(4) = 1/4, -3/2 <= -3/2}            

 

We have the following sequence of natural numbers
1, 2, 4, 7, 11, 16, 67, 83, 46, 73, 47, 85, 70, 20, 16, 76, 83, 55, 73, 56, 85, 79, 119, 934, 463, 389, 1009, 9028, 8237, 7357, 7567, 7688, 8899, 10021, 12035, 53056, 65071, 17093, 39109, 90232, 23249, 94273, 37291, 19316, 61435, 53461, 16481, 18508, 80629, 92657, 75679, 97708, 80831, 13861, 16885, 58916, 62041, 14083, 38099, 99142, 24259, 95303, 30421, 12466, 66485, 58531, 13651, 15698, 89719, 91867, 76889, 98938, 84061, 16121, 12235, 53296, 69311, 11473, 37489, 98552, 25669, 96733, 33851, 15916, 62035, 53111, 11221, 12298, 89309, 90487, 78499, 99578, 87691, 19771, 17885, 58966, 67081, 18173, 37279, 97372, 27479, 97573, 37681, 18776, 67885, 58981, 19091, 19198, 89299, 99407, 70609, 90718, 81821, 12931, 14035, 53156, 65251, 15373, 37469, 96592, 29689, 98813, 32011, 11146, 64235, 53371, 17461, 16598, 89689, 98827, 73019, 91168, 86251, 15401, 10585, 58636, 63821, 12973, 38059, 95222, 22399, 99463, 36641, 14806, 60985, 59051, 15241, 14398, 89489, 98647, 74839, 93998, 90091, 19162, 26345, 54517, 71701, 10874, 47959, 96133, 33329, 92494, 49591, 19757, 75955, 56122, 22331, 13489, 98599, 99758, 85969, 97129, 92351, 15502, 20725, 52877, 78001, 10264, 46379, 97543, 34759, 95924, 43141, 14317, 71525, 52702, 20911, 12089, 98209, 90478, 87599, 99769, 96991, 20162, 26296, 69457, 75692, 29854, 46090, 9263, 3829, 9484, 5051, 1708, 8275, 5933, 3601, 1270, 929, 1138, 8521, 1469, 9853, 3802, 2297, 8137, 7534, 4574, 4972, 3013, 3323, 3454, 4765, 5897, 8209, 9253, 3755, 5800, 313, 542, 475, 805, 740, 280, 316, 848, 1084, 5038, 8543, 3697, 8203, 3269, 9865, 5932, 2639, 9607, 7315, 5384, 5083, 4054, 4754, 4825, 5536, 6608, 8320, 493, 650, 313, 571, 434, 694, 757, 1019, 9364, 4903, 3359, 9799, 10246, 64469, 96715, 52039, 93296, 69511, 11869, 97085, 58354, 45661, 16931, 14239, 93520, 2819, 9463, 3931, 1676, 7045, 5692, 3251, 1810, 469, 1253, 3811, 1474, 5033, 3598, 9247, 7724, 4573, 4051, 1802, 2380, 1132, ... .
 What is the next term? Is it possible to find that with Maple? The Lagrange polynomial is not taken into account. I'd like to recall a great answer by Carl Love to a similar question.  However, the current situation seems to be different. The Predict command of Mma fails here.

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> restart; with(PDETools), with(plots);
> n := .3; Pr := 7; Da := 0.1e-4; Nb := .1; Nt := .1; tau := 5;
> Eq1 := (1-n)*(diff(f(x, y), `$`(y, 3)))+(1+x*cot(x))*f(x, y)*(diff(f(x, y), `$`(y, 2)))-(diff(f(x, y), y))/Da+(diff(f(x, y), y))^2+n*We*(diff(f(x, y), `$`(y, 2)))*(diff(f(x, y), `$`(y, 3)))+sin(x)*(theta(x, y)+phi(x, y))/x = x*((diff(f(x, y), y))*(diff(f(x, y), y, x))+(diff(f(x, y), `$`(y, 2)))*(diff(f(x, y), x)));
> Eq2 := (diff(theta(x, y), `$`(y, 2)))/Pr+Nt*(diff(theta(x, y), y))^2/Pr+Nb*(diff(phi(x, y), y))*(diff(theta(x, y), y))/Pr+(1+x*cot(x))*f(x, y)*(diff(theta(x, y), y)) = x*((diff(f(x, y), y))*(diff(theta(x, y), x))+(diff(theta(x, y), y))*(diff(f(x, y), x)));
> Eq3 := Nb*(diff(phi(x, y), `$`(y, 2)))/(tau*Pr)+Nt*(diff(theta(x, y), `$`(y, 2)))/(tau*Pr)+(1+x*cot(x))*f(x, y)*(diff(phi(x, y), y)) = x*((diff(f(x, y), y))*(diff(phi(x, y), x))+(diff(phi(x, y), y))*(diff(f(x, y), x)));
> ValWe := [0, 5, 10];
> bcs := {Nb*(D[2](phi))(x, 0)+Nt*(D[2](theta))(x, 0) = 0, f(0, y) = ((1/12)*y)^2*(6-8*((1/12)*y)+3*((1/12)*y)^2), f(x, 0) = 0, phi(0, y) = -.5*y, phi(x, 12) = 0, theta(0, y) = (1-(1/12)*y)^2, theta(x, 0) = 1, theta(x, 12) = 0, (D[2](f))(x, 0) = Da^(1/2)*(D[2, 2](f))(x, 0)+Da*(D[2, 2, 2](f))(x, 0), (D[2](f))(x, 12) = 0};
> pdsys := {Eq1, Eq2, Eq3}; for i to 3 do We := ValWe[i]; ans[i] := pdsolve(pdsys, bcs, numeric) end do;
> p1 := ans[1]:-plot(theta(x, y), x = 1, color = blue); p2 := ans[2]:-plot(theta(x, y), x = 1, color = green); p3 := ans[3]:-plot(theta(x, y), x = 1, color = black);
> plots[display]({p1, p2, p3});
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