> ## Documentation Index > Fetch the complete documentation index at: https://axiom.co/docs/llms.txt > Use this file to discover all available pages before exploring further. # Time series funtions > This section explains how to use time series functions in APL. The table summarizes the time series functions available in APL. | Function | Description | | -------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------ | | [series\_abs](/apl/scalar-functions/time-series/series-abs) | Returns the absolute value of a series. | | [series\_acos](/apl/scalar-functions/time-series/series-acos) | Returns the inverse cosine (arccos) of a series. | | [series\_add](/apl/scalar-functions/time-series/series-add) | Performs element-wise addition between two series. | | [series\_asin](/apl/scalar-functions/time-series/series-asin) | Returns the inverse sine (arcsin) of a series. | | [series\_atan](/apl/scalar-functions/time-series/series-atan) | Returns the inverse tangent (arctan) of a series. | | [series\_ceiling](/apl/scalar-functions/time-series/series-ceiling) | Rounds each element up to the nearest integer. | | [series\_cos](/apl/scalar-functions/time-series/series-cos) | Returns the cosine of a series. | | [series\_cosine\_similarity](/apl/scalar-functions/time-series/series-cosine-similarity) | Calculates the cosine similarity between two series. | | [series\_divide](/apl/scalar-functions/time-series/series-divide) | Performs element-wise division between two series. | | [series\_dot\_product](/apl/scalar-functions/time-series/series-dot-product) | Calculates the dot product between two series. | | [series\_equals](/apl/scalar-functions/time-series/series-equals) | Compares each element in a series to a specified value and returns a boolean array. | | [series\_exp](/apl/scalar-functions/time-series/series-exp) | Calculates the exponential (e^x) of each element in a series. | | [series\_fft](/apl/scalar-functions/time-series/series-fft) | Performs a Fast Fourier Transform on a series, converting time-domain data into frequency-domain representation. | | [series\_fill\_backward](/apl/scalar-functions/time-series/series-fill-backward) | Fills missing values by propagating the last known value backward through the array. | | [series\_fill\_const](/apl/scalar-functions/time-series/series-fill-const) | Fills missing values with a specified constant value. | | [series\_fill\_forward](/apl/scalar-functions/time-series/series-fill-forward) | Fills missing values by propagating the first known value forward through the array. | | [series\_fill\_linear](/apl/scalar-functions/time-series/series-fill-linear) | Fills missing values using linear interpolation between known values. | | [series\_fir](/apl/scalar-functions/time-series/series-fir) | Applies a Finite Impulse Response filter to a series using a specified filter kernel. | | [series\_floor](/apl/scalar-functions/time-series/series-floor) | Rounds down each element in a series to the nearest integer. | | [series\_greater](/apl/scalar-functions/time-series/series-greater) | Returns the elements of a series that are greater than a specified value. | | [series\_greater\_equals](/apl/scalar-functions/time-series/series-greater-equals) | Returns the elements of a series that are greater than or equal to a specified value. | | [series\_ifft](/apl/scalar-functions/time-series/series-ifft) | Performs an Inverse Fast Fourier Transform on a series, converting frequency-domain data back into time-domain representation. | | [series\_iir](/apl/scalar-functions/time-series/series-iir) | Applies an Infinite Impulse Response filter to a series. | | [series\_less](/apl/scalar-functions/time-series/series-less) | Returns the elements of a series that are less than a specified value. | | [series\_less\_equals](/apl/scalar-functions/time-series/series-less-equals) | Returns the elements of a series that are less than or equal to a specified value. | | [series\_log](/apl/scalar-functions/time-series/series-log) | Returns the natural logarithm of each element in a series. | | [series\_magnitude](/apl/scalar-functions/time-series/series-magnitude) | Calculates the Euclidean norm (magnitude) of a series. | | [series\_max](/apl/scalar-functions/time-series/series-max) | Returns the maximum value from a series. | | [series\_min](/apl/scalar-functions/time-series/series-min) | Returns the minimum value from a series. | | [series\_multiply](/apl/scalar-functions/time-series/series-multiply) | Performs element-wise multiplication of two series. | | [series\_not\_equals](/apl/scalar-functions/time-series/series-not-equals) | Returns the elements of a series that aren’t equal to a specified value. | | [series\_pearson\_correlation](/apl/scalar-functions/time-series/series-pearson-correlation) | Calculates the Pearson correlation coefficient between two series. | | [series\_pow](/apl/scalar-functions/time-series/series-pow) | Raises each element in a series to a specified power. | | [series\_sign](/apl/scalar-functions/time-series/series-sign) | Returns the sign of each element in a series. | | [series\_sin](/apl/scalar-functions/time-series/series-sin) | Returns the sine of a series. | | [series\_stats](/apl/scalar-functions/time-series/series-stats) | Computes comprehensive statistical measures for a series. | | [series\_stats\_dynamic](/apl/scalar-functions/time-series/series-stats-dynamic) | Computes statistical measures and returns them in a dynamic object format. | | [series\_subtract](/apl/scalar-functions/time-series/series-subtract) | Performs element-wise subtraction between two series. | | [series\_sum](/apl/scalar-functions/time-series/series-sum) | Returns the sum of a series. | | [series\_tan](/apl/scalar-functions/time-series/series-tan) | Returns the tangent of a series. | Time series functions operate on dynamic arrays where the values are real numbers.