Calibration data

Apparatus, comprising at least one processor, at least one memory, and computer-readable code stored on the at least one memory, wherein the computer-readable code when executed controls the at least one processor to perform a method comprising:

• storing at least one three-dimensional matrix C[M][N][K] of calibration data;
• performing singular value decomposition of each at least one three-dimensional matrix C[M] [N] [K] of calibration data to produce at least one first unitary rotation matrix U, at least one diagonal scaling matrix S and at least one second unitary rotation matrix V;
• and
• resizing each of the at least one first unitary rotation matrix U, the at least one diagonal scaling matrix S and the at least one second unitary rotation matrix V by removing dimensions therefrom, thereby producing resized matrices U, S and V.

Apparatus, comprising at least one processor, at least one memory, and computer-readable code stored on the at least one memory, wherein the computer-readable code when executed controls the at least one processor to perform a method comprising:

• receiving data;
• using the received data to reconstruct plural matrices of compressed calibration data, the plural matrices comprising at least one first unitary rotation matrix U, at least one diagonal scaling matrix S and at least one second unitary rotation matrix V;
• and
• performing matrices multiplication of U, S and V to obtain the reconstructed matrices.