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Article contents:== Outdated egg! This is an egg for CHICKEN 4, the unsupported old release. You're almost certainly looking for [[/eggref/5/interp1d|the CHICKEN 5 version of this egg]], if it exists. If it does not exist, there may be equivalent functionality provided by another egg; have a look at the [[https://wiki.call-cc.org/chicken-projects/egg-index-5.html|egg index]]. Otherwise, please consider porting this egg to the current version of CHICKEN. [[tags:egg]] == interp1d One-dimensional numerical interpolation. [[toc:]] == Usage (require-extension interp1d) == Documentation The {{interp1d}} library provides routines for linear and piecewise quadratic interpolation, as well as a facility for "sliding window" interpolation over a long, or possibly infinite, sequence of data. === Procedures <procedure>interp1d:nearest:: XDATA * YDATA * X -> Y</procedure> Interpolates function {{y=f(x)}} at the point {{x}} using the data point nearest to {{x}}. Arguments {{XDATA}} and {{YDATA}} are lists of numeric values that correspond to sample points of the function being interpolated. Argument {{X}} must be within the range of values contained in {{XDATA}}. <procedure>interp1d:linear:: XDATA * YDATA * X -> Y</procedure> Interpolates function {{y=f(x)}} at the point {{x}} using the linear interpolation method. Arguments {{XDATA}} and {{YDATA}} are lists of numeric values that correspond to sample points of the function being interpolated. Argument {{X}} must be within the range of values contained in {{XDATA}}. <procedure>interp1d:piecewise-quadratic:: XDATA * YDATA * X -> Y</procedure> Interpolates function {{y=f(x)}} at the point {{x}} using the piecewise quadratic interpolation method. Arguments {{XDATA}} and {{YDATA}} are lists of numeric values that corresponds to sample points of the function being interpolated. Argument {{X}} must be within the range of values contained in {{XDATA}}. <procedure>interp1d:from-sequence:: METHOD * STEP * YDATA [* START * CAR * CDR * NULL? * DELTA-WINDOW-LEN * MAX-WINDOW-LEN] -> (LAMBDA X -> Y)</procedure> Constructs a sliding window interpolation procedure, for a given sequence {{YDATA}} that contains uniformly sampled values of a function {{y = f(x)}}, where {{X}} has an initial value of {{START}} (default 0) and is incremented by {{STEP}} amount. The returned procedure performs interpolation using the given {{METHOD}} procedure, while the window is shifted forwards by the appropriate amount if {{X}} is outside the current window range. Backward shifting is not supported. Argument {{METHOD}} is one of the interpolation procedures above. Optional argument {{START}} specifies the initial (smallest) {{X}} and defaults to 0. Optional arguments {{CAR}}, {{CDR}}, {{NULL?}} are used to access {{YDATA}} and default to the standard list procedures. If the input sequence is not a list (e.g. an SRFI-40 stream), these arguments can be used to specify the appropriate accessors and predicates. Optional arguments {{DELTA-WINDOW-LEN}} and {{MAX-WINDOW-LEN}} specify the window increment (default 4) and maximum window size (default 128). <procedure>interp1d:lbound:: XDATA * YDATA * X -> Y</procedure> Returns the value of the data point nearest to {{X}} that does not exceed the value of {{X}}. <procedure>interp1d:ubound:: XDATA * YDATA * X -> Y</procedure> Returns the value of the data point nearest to {{X}} that is larger than {{X}}. == Examples == About this egg === Author [[/users/ivan-raikov|Ivan Raikov]] === Version history ; 1.12 : Eliminated dependency on easyffi ; 1.11 : Documentation converted to wiki format ; 1.10 : Ported to Chicken 4 ; 1.9 : Removed testeez as a dependency ; 1.8 : Added lbound and ubound routines ; 1.7 : Added nearest interpolation method ; 1.6 : Bug fix in bounds routine ; 1.5 : Bug fix in the sliding window routine for the case of non-list input data ; 1.4 : Added a proper error message routine ; 1.3 : Added a boundary exceeded error message to the sliding window routine ; 1.2 : Build script updated for better cross-platform compatibility ; 1.1 : Documentation updates ; 1.0 : Initial release === License Copyright 2007-2012 Ivan Raikov and the Okinawa Institute of Science and Technology This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A full copy of the GPL license can be found at <http://www.gnu.org/licenses/>. Description of your changes:

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