indexing matrices

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Mon, 07/04/2016 - 08:22 pm

Dear all,
I'm not very experienced in programming and kind of stuck right now.
I am trying to implement the following loop on matrix calculations.
All matrices are 3x3

//R[0]= intial condition matrix
//I =identity matrix
//B= matrix

//k1,k2 = scalars


For (i=1;i<100;i+=1)
//calculate k1,k2
// calculate B


R[i]=R[i -1] x ( I + k1*B + k2*B^2)

///do some calculations using R[i]

// delete R[i-1]


endfor


Could somebody help?
If that's the extent of your code, you're missing a few things. First, you need to declare your matrices with a WAVE statement. The scalars need to be declared as variables. It's also not a good idea to call the Identity matrix I. As you can see, i has a special meaning and Igor is case insensitive. The loop that you've written goes some way beyond your data. The number in square brackets refers to row number in your matrix, I'm guessing you need to do this on multiple matrices? The expression in the loop also won't work, because igor needs to know exactly which points it needs to work with. For your matrix calculations you are better doing MatrixOp.

July 4, 2016 at 09:52 pm - Permalink

Function MatrixProc1(matR, matB, k1, k2)
 Wave matR, matB
 Variable k1, k2
 
 Variable i
 For (i = 1; i < 100; i += 1)
  //calculate k1, k2
  //calculate matB
 
  MatrixOp matR = matR x (Identity(3) + k1 * matB + k2 * matB x matB)
 
  // do some calculations using matR
 endfor
end


If matB is not specified initially and matB will not be used in other procedure,

Function MatrixProc2(matR, k1, k2)
 Wave matR
 Variable k1, k2
 
 Make /N=(3, 3) /O matB
 Variable i
 For (i = 1; i < 100; i += 1)
  //calculate k1, k2
  //calculate matB
 
  MatrixOp matR = matR x (Identity(3) + k1 * matB + k2 * matB x matB)
 
  // do some calculations using matR
 endfor
 KillWaves /Z matB
end

July 4, 2016 at 10:22 pm - Permalink

sjr51 wrote:
If that's the extent of your code, you're missing a few things. First, you need to declare your matrices with a WAVE statement. The scalars need to be declared as variables. It's also not a good idea to call the Identity matrix I. As you can see, i has a special meaning and Igor is case insensitive. The loop that you've written goes some way beyond your data. The number in square brackets refers to row number in your matrix, I'm guessing you need to do this on multiple matrices? The expression in the loop also won't work, because igor needs to know exactly which points it needs to work with. For your matrix calculations you are better doing MatrixOp.


dear SJR51,
Thank for trying to help. The above is not an extent of my code, but more a sketch of want I want to accomplish. I know how to do the declarations, and I understand the matrix indexing. Basically, I believe my struggle resumes to this:

1. how to index a matrix as a whole inside a loop.
2. Matrixop does not seem to handle indexing. how can I use indexing inside a Matrixop operation?

Thanks

July 4, 2016 at 11:23 pm - Permalink

kanekaka wrote:
Function MatrixProc1(matR, matB, k1, k2)
 Wave matR, matB
 Variable k1, k2
 
 Variable i
 For (i = 1; i < 100; i += 1)
  //calculate k1, k2
  //calculate matB
 
  MatrixOp matR = matR x (Identity(3) + k1 * matB + k2 * matB x matB)
 
  // do some calculations using matR
 endfor
end


If matB is not specified initially and matB will not be used in other procedure,

Function MatrixProc2(matR, k1, k2)
 Wave matR
 Variable k1, k2
 
 Make /N=(3, 3) /O matB
 Variable i
 For (i = 1; i < 100; i += 1)
  //calculate k1, k2
  //calculate matB
 
  MatrixOp matR = matR x (Identity(3) + k1 * matB + k2 * matB x matB)
 
  // do some calculations using matR
 endfor
 KillWaves /Z matB
end


Dear Kanekaka

That solved my problem!
I thought I couldn't use the destination matrix on both sides of the argument of Matrixop, but this is only the case for 3d waves.

Thank you!

July 5, 2016 at 12:20 am - Permalink