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Thread Subject:
Matrix Integration!

Subject: Matrix Integration!

From: Teto

Date: 7 Apr, 2009 16:17:01

Message: 1 of 3

I’m trying to integrate a matrix function of 40 x 40. The y & x intervals are equal (0.5), for example, x0=0.5, x1=1, x2=1.5…etc. The problem is the resulting data are not integral values. I have applied the following code

Syms x
Int (M, x)

Part of the results is shown below
[0, 0, -57/10*x]
[ 1/2*x, 0, -27/5*x]
[ x, 0, -97/20*x]
[ 3/2*x, 0, -27/10*x]
[ 2*x, 0, -109/20*x]
[ 5/2*x, 0, -93/20*x]

When I defined the x values, it just replaces the x with the defined values without any change!
Does anyone know how I can get the results with integral values? Many thanks in advance.

Teto

Subject: Matrix Integration!

From: Roger Stafford

Date: 7 Apr, 2009 16:59:01

Message: 2 of 3

"Teto " <tetomiko@yahoo.co.uk> wrote in message <grfu9t$nv$1@fred.mathworks.com>...
> I’m trying to integrate a matrix function of 40 x 40. The y & x intervals are equal (0.5), for example, x0=0.5, x1=1, x2=1.5…etc. The problem is the resulting data are not integral values. I have applied the following code
>
> Syms x
> Int (M, x)
>
> Part of the results is shown below
> [0, 0, -57/10*x]
> [ 1/2*x, 0, -27/5*x]
> [ x, 0, -97/20*x]
> [ 3/2*x, 0, -27/10*x]
> [ 2*x, 0, -109/20*x]
> [ 5/2*x, 0, -93/20*x]
>
> When I defined the x values, it just replaces the x with the defined values without any change!
> Does anyone know how I can get the results with integral values? Many thanks in advance.
>
> Teto

  What you have shown here is certainly not the correct way to do integration, Teto. As far as I can tell, in writing "Int (M, x)" you have found a symbolic matrix of indefinite integrals with respect to x for each of the constants in a matrix M, which is not at all what I think you are after. Also why do you expect "integral values" in these results?

  You need to explain in much greater detail what it is you are attempting to do. We cannot help you unless you do. What you have shown us so far makes no sense.

Roger Stafford

Subject: Matrix Integration!

From: Teto

Date: 16 Apr, 2009 07:06:04

Message: 3 of 3

"Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <grg0ol$ifp$1@fred.mathworks.com>...
> "Teto " <tetomiko@yahoo.co.uk> wrote in message <grfu9t$nv$1@fred.mathworks.com>...
> > I’m trying to integrate a matrix function of 40 x 40. The y & x intervals are equal (0.5), for example, x0=0.5, x1=1, x2=1.5…etc. The problem is the resulting data are not integral values. I have applied the following code
> >
> > Syms x
> > Int (M, x)
> >
> > Part of the results is shown below
> > [0, 0, -57/10*x]
> > [ 1/2*x, 0, -27/5*x]
> > [ x, 0, -97/20*x]
> > [ 3/2*x, 0, -27/10*x]
> > [ 2*x, 0, -109/20*x]
> > [ 5/2*x, 0, -93/20*x]
> >
> > When I defined the x values, it just replaces the x with the defined values without any change!
> > Does anyone know how I can get the results with integral values? Many thanks in advance.
> >
> > Teto
>
> What you have shown here is certainly not the correct way to do integration, Teto. As far as I can tell, in writing "Int (M, x)" you have found a symbolic matrix of indefinite integrals with respect to x for each of the constants in a matrix M, which is not at all what I think you are after. Also why do you expect "integral values" in these results?
>
> You need to explain in much greater detail what it is you are attempting to do. We cannot help you unless you do. What you have shown us so far makes no sense.
>
> Roger Stafford

Thanks Roger and sorry for being late to reply you, herein I give some details and hope you help me

I have a function in a first derivative form (dF/dz), this function is measured, so (dF/dz) = numerical values in a matrix form, every numerical value in this matrix represent the measurements of (dF/dz) at x, y, for example, (dF1/dz)= 5 at x1 and y1, (dF2/dz)= 2.3 at x1 and y2,…etc. Because the instrument measures directly the value of (dF/dz), and z is known, I want to know how to get numerically F as a separate value using the integration. Is there any solution to get only F by using the matrix integration? Please suggest. Many thanks.

Teto

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