www.gusucode.com > distcomp 案例源码程序 matlab代码 > distcomp/pctdemo_aux_quadpi.m
function y = pctdemo_aux_quadpi(x) %PCTDEMO_AUX_QUADPI Return data to approximate pi. % Helper function used to approximate pi. This is the derivative % of 4*atan(x). % Copyright 2008 The MathWorks, Inc. y = 4./(1 + x.^2);