Ok guys this is the problem i have a matrix wich is really the result of a semivariogram so it is like this 
thi is my semivariogram so i have to find the best model and fit it to it, i can't just throw a polynomial it has to be
spherical= h:= C((3/2)*x/a-(1/2)*x^3/a^3) 
expotencial=
Lineal= y:= p*x
or y:=p*x^a

so i want the maple to show me the variogram plot and the i select wich one of the models i will apply.
the problem is that i don't know how to apply the models so started something that could maybe lead to the values of C and A for the spherical and the xpotencial becouse the others too are easy.
------------------------------------------------------------------.--------------------------------------------------------
restart;
with(plots);
with(CurveFitting);
m3 := Matrix([[0, 0], [1, 2], [2, 5], [3, 7], [4, 10], [5, 14], [6, 15], [7, 15.4], [8, 15.8], [9, 16], [10, 16.4]]);
plot(m3);
Upsilon := C(1-exp(-x/a));
Upsilon := C((3/2)*x/a-(1/2)*x^3/a^3);
for C to 16 do
for a to 100 do
for x to 11 do
H := m3(x, 2);
R[C, a, x] := abs(Upsilon-H)
end do
end do
end do;
for r to 16 do
for j to 100 do
N[r, j] := sum(R[r, j, X], X = 1 .. 11);
if N[r, j] < 55 then
print(r, j)
end if
end do
end do;
k := 14*(3/2*((1/16)*xx)-(1/2)*xx^3/16^3);
multiple(plot, [m3, color = "Green"], [k, xx = 0 .. 11, color = "Blue"])
----------------------------------------------------------...................---------------------------------------
so in this code i rest the values of the model and the values of the matrix for differents C and a so i pick the min of the Sum to see wich C and a give me the min value but i didn't work quite well first is difficult to get the C and a and sometimes the new curve is just not similir to the semivariogram (Matrix) please help i tried 
k := NonlinearFit(C((3/2)*x/a-(1/2)*x^3/a^3), X, Y, x)
and 
k:=LeastSquares`(m3, v, curve = C*(1-exp(-x/a)))
but they don't let me because they aint linear on the parameters
please help 
if you are interested in this topic here is what i am trying to do but explained really well is for geological matters
http://www.kriging.com/PG1979/index.htm#Chapter_2+Part1

if want to help me use this matrix 
m3:= Matrix([[0, 0], [1, 1], [2, 3], [3, 5], [4, 7], [5, 8], [6, 9], [7, 10], [8, 10.5], [9, 10], [10, 9.8], [11, 9.8], [12, 10.5], [13, 10.89], [14, 11.2], [15, 10.6], [16, 9.85], [17, 9.45], [18, 9.77], [19, 10.15], [20, 10.7], [21, 10.04], [22, 10], [23, 10.85], [24, 10.7], [25, 10.94], [26, 10.81], [27, 10.33]])
for that matrix the spherical model is the best i know

goodbye

Developed and then implemented with open code components. It is very important to note this post is held for students of civil engineering and mechanics. Using advanced mathematical concepts to concepts in engineering.

Metodos_Energeticos_full.mw

(in spanish)

Atte.

L.Araujo.C

I have a table whose indices and entries are strings, as in:

    T := table(["green" = "gruen", "red" = "rot", "blue" = "blau"]);

Thus, T["green"] evaluates to "gruen" but T["asdf"] evaluates to T"asdf".

What is a good way to detect that "green" is a predefined index into the table but "asdf" is not?  I do it in a somewhat clumsy way, as in:

> has("green", [indices(T, 'nolist')]);
        true

> has("asdf", [indices(T, 'nolist')]);
        false

I suspect that there ought to be a less elaborate way of doing that.

I'm currently having some difficulties in solving a system of differential equations numerically.

This is my code.

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Dear Friends:

I am currently working on a calculation for phase velocity of acoustic waves and don’t get along.  

My equation has the following form:

equ := tan( (31 / 20000) * sqrt( -9610000/c^2 + 1) / Pi) / tan((961/1260000) * sqrt( -39690000/c^2 + 1)/ P i) = -(1191640000/63)*sqrt(-9610000/c^2 + 1)*sqrt (-39690000/c^2 + 1)/ (c^2*(19220000/c^2 - 1)^2)

Using ‘sol = solve(equ,c)’ returns

sol := 96100* RootOf(1 + (400000000 * Pi^2 * RootOf(40320000000000000000 * Pi^4 * tan(_Z)*_Z^4256000000000000 * Pi^3 * csgn(_Z) * _Z^3 * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) -96868800000000 * Pi^2 * tan(_Z) * _Z^2 + 615040000 * Pi * csgn(_Z) * _Z * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi ) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167)+58181823 * tan(_Z))^2 - 961)* _Z^2)

c should be in a range of 13,000.

Two questions:

1) How can I deal with _Z?

2) Any suggestion how I can calculate ‘c’? Maybe numerical?

I am relative new in maple…

Many thanks!

Alex

Hi,

Might be a silly question but how do I preview/display the expression I type instead of maple automatically solving it.

For example, If I type in '1+1' in wolfram, it displays 'input: '1+1'' right below it.

I would like to do this in maple but cant seem to figure it out.

Hopefully that made some sense.

Cheers and thanks! 

Int(piecewise(t < T1, exp((1/2)*t*(1+2*I-I*sqrt(3))), t < T2, -1000*exp((1/2)*t*(1+2*I-I*sqrt(3)))*(-1/1000+T1-t), T2 <= t, -1000*exp((1/2)*t*(1+2*I-I*sqrt(3)))*(-1/1000-T2+T1)), t)

The help of maple software is not so clear , and I cant understand the exact way which leads to exporting a matrix from maple to matlab. more precisely how I can link between maple and matlab .

would you please with an example show me the rule.

I just wanted to ask whether one can get out of the expansion

(D-f(x))@@2(g)(x)=(D@@2)(g)(x)-(D((f(x))(g)))(x)-((f(x))(D(g)-(f(x))(g)))(x)

the intended result

(D@@2)(g)(x)-D(f*g)(x)-f(x)*D(g)(x)+f(x)^2*g(x)

Can we rotate 3d text in Maple like this shown here?

http://mathematica.stackexchange.com/questions/25065/rotating-3d-text

Let us consider the definite integral

J:=int(abs(x-(-x^5+1)^(1/5)), x = 0 .. 1);

Maple fails with it, Mathematica 10.1 finds it in terms of  special functions. Let us look at the integrand:
plot(x-(-x^5+1)^(1/5), x = 0 .. 1);

We see the expression under the modulus changes its sign at the unique point of RealRange(0,1). Therefore

solve(x-(-x^5+1)^(1/5));

Then

J:= int(-x+(-x^5+1)^(1/5), x = 0 .. (1/2)*2^(4/5))+int(x-(-x^5+1)^(1/5), x = (1/2)*2^(4/5) .. 1);

which outputs a complicated expression

(1/8)*2^(4/5)*(4*hypergeom([-1/5, 1/5], [6/5], 1/2)-2^(4/5))+(1/2)*2^(4/5)*((1/2)*2^(1/5)-(1/4)*2^(4/5))-(1/25)*Pi*csc((1/5)*Pi)*(-(25/2)*sin((1/5)*Pi)*GAMMA(4/5)*2^(4/5)*hypergeom([-1/5, 1/5], [6/5], 1/2)/Pi+(5/4)*sec((3/10)*Pi)*cos((1/10)*Pi)*2^(3/5)*Pi^(1/2)*csc((3/10)*Pi)/GAMMA(7/10))/GAMMA(4/5).

At the same time we have

int(abs(x-(-x^5+1)^(1/5)), x = 0 .. 1, numeric);

                          0.5000000000

How to obtain 1/2 symbolically?

I am trying to integrate product of exp(t+s) and a piecewise polynomial but the result can not be read and not usefull. also I used numerical integration function "Quadrature" but the result did not change.

error.mwerror.mw