## KLT_FeatureHistory

## `typedef struct {
int nFrames;
KLT_Feature *feature;
} *KLT_FeatureHistory;
`

A KLT_FeatureHistory is an array of features. The `nFrames` field indicates the number of features allocated, or rather the number of frames in which the feature's data is given. It must not be changed manually.

NOTE: Although a feature list and a feature history look similar, the former is intended to refer to an array of features from a single image, while the latter refers to the same feature tracked through several images.

The following code illustrates how to access the data in a feature history:

    KLT_FeatureHistory fh;
    int frame;

    for (frame = 0 ; frame < fh->nFrames ; frame++)  {
         printf("(%5.1f,%5.1f) = %d\n",
              fh->feature[frame]->x,
              fh->feature[frame]->y,
              fh->feature[frame]->val);
    }