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The definition of instantaneous frequency is the time rate of change of phase, or (), where () is the instantaneous phase of a signal. We can know the instantaneous frequency from the time–frequency plane directly if the image is clear enough.
In information retrieval, tf–idf (also TF*IDF, TFIDF, TF–IDF, or Tf–idf), short for term frequency–inverse document frequency, is a measure of importance of a word to a document in a collection or corpus, adjusted for the fact that some words appear more frequently in general. [1]
Time for prints (or trade for prints, time for pics, TFP, and sometimes prints for time, PFT) is a term that describes an arrangement between a model and a photographer whereby the photographer agrees to provide the model with a certain number of pictures of selected photographs from the session, and a release or license to use those pictures in return for the model's time.
Vector space model or term vector model is an algebraic model for ... also known as (term) weights, have been developed. One of the best known schemes is tf-idf ...
A signal, as a function of time, may be considered as a representation with perfect time resolution.In contrast, the magnitude of the Fourier transform (FT) of the signal may be considered as a representation with perfect spectral resolution but with no time information because the magnitude of the FT conveys frequency content but it fails to convey when, in time, different events occur in the ...
In a classification task, the precision for a class is the number of true positives (i.e. the number of items correctly labelled as belonging to the positive class) divided by the total number of elements labelled as belonging to the positive class (i.e. the sum of true positives and false positives, which are items incorrectly labelled as belonging to the class).
The bag-of-words model (BoW) is a model of text which uses a representation of text that is based on an unordered collection (a "bag") of words. It is used in natural language processing and information retrieval (IR). It disregards word order (and thus most of syntax or grammar) but captures multiplicity.
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a system.