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**General discussions (Q&As) / ref frames question**

« **on:**October 09, 2007, 09:59:08 am »

I asked a question about a month or so ago regarding the ref_frames.dat file. In fact, I think I have discovered my original problem, and I thought it useful to report it here.

Please correct me if I am wrong!!! The notation in the ref_frames.dat file was actually the transpose of what I thought! I would typically notate a 3d reference frame as follows:

[a11, a12, a13] <- X Components of Axis Vectors

[a21, a22, a23] <- Y Components of Axis Vectors

[a31, a32, a33] <- Z Components of Axis Vectors

i.e. the x-axis vector is composed of elements [a11, a21, a31]

However, it appears from your file that the ref_frames.dat is actually the transpose of this! That is why I originally reported that the frames "appear to be pointing in unusual directions!" Let me clarify... The ref_frames.dat file instead outputs

[a11, a12, a13] <- X Axis Vectors

[a21, a22, a23] <- Y Axis Vectors

[a31, a32, a33] <- Z Axis Vectors

i.e. the x-axis vector is composed of elements [a11, a12, a13]

Is that right? If so, did I miss somewhere that this is explicitly stated? I am used to using a different convention!

Thanks,

Kevin

Please correct me if I am wrong!!! The notation in the ref_frames.dat file was actually the transpose of what I thought! I would typically notate a 3d reference frame as follows:

[a11, a12, a13] <- X Components of Axis Vectors

[a21, a22, a23] <- Y Components of Axis Vectors

[a31, a32, a33] <- Z Components of Axis Vectors

i.e. the x-axis vector is composed of elements [a11, a21, a31]

However, it appears from your file that the ref_frames.dat is actually the transpose of this! That is why I originally reported that the frames "appear to be pointing in unusual directions!" Let me clarify... The ref_frames.dat file instead outputs

[a11, a12, a13] <- X Axis Vectors

[a21, a22, a23] <- Y Axis Vectors

[a31, a32, a33] <- Z Axis Vectors

i.e. the x-axis vector is composed of elements [a11, a12, a13]

Is that right? If so, did I miss somewhere that this is explicitly stated? I am used to using a different convention!

Thanks,

Kevin