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+====== ztrans ======
+===== Motivation =====
+Under certain circumstances (e.g. data that is arbitrarily scaled and comes from several sources has to be compared), one way to normalize (re-scale) the data is to apply z-transformation (setting the mean of values in the desired dimension to 0 and the standard deviation to 1).
+===== Function reference ('help ztrans') =====
+<file>  ztrans  - perform z-transformation on time course
+  FORMAT:       [ztc, zf, zsh] = ztrans(tc [, dim [, tp]])
+  Input fields:
+        tc          time course data
+        dim         temporal dimension (default: first non-singleton)
+        tp          time points (indices of dim to use for normalization)
+  Output fields:
+        ztc         z-transformed time course
+        zf          z-transformation factor
+        zsh         z-transformation shift
+  See also psctrans</file>
+===== Usage examples =====
+  * z-transforming a single time-course (e.g. of a region or voxel):<code matlab>ztc = ztrans(tc);</code>
+  * z-transformation of an entire VTC (ensuring that dimension is 1):<code matlab>vtc.VTCData = ztrans(vtc.VTCData, 1);</code>
+  * z-transformation of 4D-NII VoxelData (ensuring that dimension is 4):<code matlab>nii.VoxelData = ztrans(nii.VoxelData, 4);</code>
+  * also obtaining the information about the scaling factor and shift:<code matlab>[ztc, zfactor, zshift] = ztrans(tc);</code>
+  * only using values where no experimental condition in an SDM is active:<code matlab>% find timepoints to use
+tp = all(abs(sdm.SDMMatrix(:, 1:sdm.FirstConfoundPredictor-1)) < 0.1, 2);
+% apply z-transformation with those as normalization basis
+vtc.VTCData = ztrans(vtc.VTCData, 1, tp);</code>