Items tagged with spline

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so i  got this code:

But it cannot Find a value for M (wich would be the maximum distance between) it literaly stays working for severeal minutes and necer gives an answer, also i cant find a function to do this for every value for n (n-1 steps from a to b), also would mean that xy would need to get more points, any idea of how can i solve this for any n? or at least fix the problem with M, and i do the steps from a to b Manually.

heeeelp me please this is driving me nuts

thanks a lot :)

I need to solve an ode of the type ay''+by'+cy=f(x) using cubic b spline.

can any one help me with the code or algorithm. Thanks

Hi, 

I'm solving a 2D grid with some finite-diference methods. The result is a surface, i.e f(x,y) = z. Where X and Y and points on a grid. 

 

I then need to integrate over this grid, i.e

int(f(x,y),[x=0..10, y=0..10]) 

I have tried interpolating the grid. I've used CurveFitting:-ArrayInterpolation() to interpolate points in this 2D space and then integrate over them. 

I'm using a 30x30 grid, but this interpolation scheme takes far too long. The function generated from the ArrayInterpolation creates an interpolation every time a point is evaluated, which I assume is why the integral is very computationally expensive. 

I would like to create a piecewise analytic function from the 2-D grid, perhaps using CurveFitting:-Spline(), however from my understanding this only works for 1D objects? 

Is there any better solution for integrating a 2D numeric grid?

Thanks in advance

Hello,

I would like to understand this code which has been discussed in the forum a moment ago.

http://www.mapleprimes.com/posts/120138-Exact-Cubic-Hermite-Spline

Here the Maple code :

alec_modified_hermit.mw

Does somebody know the theoric developpements to this code ?

May you help me to add comments so as to facilitate the link with the theory ? One line in front of each procedure should be enough for me to understand. For the moment, I didn't manage to match it with the theory.

When I would understand this code, I would like in a second step compare the result with Catmull-Rom splines.

Thanks a lot for your help.

 @acer : I think this subject may interest you

 

Hello,

I try to use a Catmull-Rom spline which has to match on several points.

I use a code extracted from the book "Geometry and curves with maple".

Here you can find an extract which is visible from google book :

I have slightly modified the initial procedure crom_2d. I didn't find the error in my procedure. May you help me to find the blocking point of my procedure ?

Here I attached my code:

CalculSplineMatmull-Rom.mw

Thank you for your help.

Hi!

This question is related to http://www.mapleprimes.com/questions/204419-Derivatives-Of-Splines-Are-Not-Defined and http://www.mapleprimes.com/questions/42114-Problem-With-Spline-Integrating , however I have not been able to apply the solutions given there to my problem.

I have a set of points given by

and certain function value points given by

where e1 is the function I am approximating.


Using

I come up with my piecewise function.

When I do diff(e4,x), however, the points at the nodes show "float(undefined) x=0.2..."(the node).

As it turns out, the value of the derivative on the left of the node is not equal to that of the right side by a factor of 10^(-7), in other words, numerically unimportant but high enough for maple to realise it is not the same number. How could I tell Maple that I am happy choosing, for example, the value given by the function on right side of the node?

I welcome any suggestions.

Many thanks in advance.

Dear,

I have this code generating a piecewise function:

> with(CurveFitting);

> points := [[0, 1], [1, 2.5], [3, 2.3], [4.2, 5], [5, 3.5], [5.8, 4.2], [7, 7], [8, 10]];

> splcurve := Spline(points, v);

In this particular case I have seven distinct polynomials. Someone knows how could I get one specific polynomial, for example, the one exactly before v < 4.2? 

In other terms:

I'd like to define a new function, say 'f', that is exactly the polynomial just before v < 4.2 (e.g, something like f:=(splcurve, v < 4.2)). Do exists this possibility? (I have been looking for it elsewhere but without success!!)

Thanks in advance! Best regards!

 

Hello, Mapleprimes' users.

 

I am using spline to fit a function to a given data (instead of polynomial). I created two examples with data of y=cos(x). 

The first example has a domain X=0..10 and its result is satisfactory.

Ths second example has a larger domain, X=0..15, but I couldn't plot the spline function. The function fits well, but its line ends at X=~10.

Then I ckecked this spline assigning several values of X, and all the results are correct. The problem is on the plot step.

My mw file is:

> restart;
> with(plots);
> with(CurveFitting);
> plotsetup(default);

First Exemple Data (Y=cos(X)):
> X := [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
> Y := [1, .54, -.41, -.99, -.65, .28, .96, .75, -.14, -.91, -.83];
> Piece1 := spline(X, Y, x, 2);
> fig1 := plot(Piece1, view = [0 .. 15, -1 .. 1]);
> fig2 := pointplot(X, Y);
> display(fig1, fig2);
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Second Example Data (Y=cos(X))::
> X := [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
> Y := [1, .54, -.41, -.99, -.65, .28, .96, .75, -.14, -.91, -.83, 0., .84, .91, .13, -.76];
> Piece2 := spline(X, Y, x, 2);
> fig3 := plot(Piece2, view = [0 .. 15, -1 .. 1]);
> fig4 := pointplot(X, Y);
> display(fig3, fig4);
> test := unapply(Piece2, x);
> test(15);

    test(15)=-0.76    #correct value!
 

 

My actual problem involves data from X=0 to X=300, and I have the same issue in this case.

Thanks.

Hey 

I'm trying to fit a spacecurve onto some points I have. 

I know, I can use Spline to do this in 2D, but it doesn't work in 3D.

What command(s) can I use to fit a spacecurve onto my points? 

Thanks in advance

well i know this blog is for maple problems and question but badly need your help guys. i want to know difference between cubic spline and cubic b-spline in simple words..

I'm sure there are other Maple users who have done these things, but I'm in the early stages of learning Maple 15 after moving (up) from Mathcad.

1. How do I plot a simple wireframe map of the world?

2. If I have a dataset of gridded data where the data is in the form [latitude, longitude, number] how do I map that data to a grid on the globe and give it a height according to the magnitude of the [number]?

3. Is there a way to smooth the heights of each...

Hi folks,

I'm trying to find the x value of my data set that corresponds to 50% of area under the curve. I've used curvefitting and splines to generate a piecewise function, and am able to find the area under the curve between my two approximated zeros (as this is the only relevant region). I would greatly appreciate any help, as I've been pulling my hair out for a couple hours now!

 

Cheers!

hi

 

I have two sets of data namely x[i] and y[i], at first i want to pass a spline from all points (points are in 2d x-y diagram) and then extract some point from that. how can i write the suitable code  in maple? 

thanks

HI,

 

I measured some points. This points are plotted in a graph. Now I want to make a fit on this points.

I now that the fit-function has to be like this:

F = A + B1 x e^(-t/C1) + B2 x e^(-t/C2)

Problem: how can I create a fitting function like that?

 

The best thing I found is the "spline"-fit, but it doesn't work properly. It has to be one lonely function, not a summary of several functions (like spline).

Following Christopher2222 request, I wrote the following procedures for "exact" cubic Hermite spline interpolation,

p:=proc(x0,p0,m0,x1,p1,m1,x)
local t,d;
d:=x1-x0;
t:=(x-x0)/d;
p0+(d*m0+(3*(p1-p0)-d*(2*m0+m1)+(2*(p0-p1)+d*(m0+m1))*t)*t)*t
end:

pb:=proc(x0,p0,x1,p1,m1,x)
local t,d;
d:=x1-x0;
t:=(x-x0)/d;
p0+(2*(p1-p0)-d*m1+(p0-p1+d*m1)*t)*t
end:

pe:=proc(x0,p0,m0,x1,p1,x...
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