On the Complexity of Computing the Logarithm and Square Root Functions on a Complex Domain

Author(s):  
Ker-I Ko ◽  
Fuxiang Yu

2007 ◽  
Vol 23 (1) ◽  
pp. 2-24 ◽  
Author(s):  
Ker-I Ko ◽  
Fuxiang Yu


1993 ◽  
Vol 2 (6) ◽  
pp. 465-479
Author(s):  
John Sumelius

A nonlinear Mitscherlich function was found to be superior to quadratic and square root functions in estimating yield response to nitrogen based on a Finnish sample of barley. Nonnested hypothesis testing (J-test) indicated the Mitscherlich functional form to fit the data better than the quadratic form based on this sample. In the analysis of the crop response for spring wheat the Mitscherlich functional form could not be proved superior by a J-test. The inferred profit maximizing nitrogen fertilization levels based on the Mitscherlich functional form exceeded the quadratic polynomial forms and were lower than the inferred levels using square root specifications. Implementing 100% nitrogen price increases or 50% producer price reductions lowered the profit maximizing nitrogen application doses by 20-24%, according to the Mitscherlich specification.





2015 ◽  
Vol Volume 20 - 2015 - Special... ◽  
Author(s):  
Augustin Fruchard ◽  
Reinhard Schäfke

International audience Difference equations in the complex domain of the form y(x+ϵ)−y(x)=ϵf(y(x))/y(x) are considered. The step size ϵ>0 is a small parameter, and the equation has a singularity at y=0. Solutions near the singularity are described using composite asymptotic expansions. More precisely, it is shown that the derivative v′ of the inverse function v of a solution (the so-called Fatou coordinate) admits a Gevrey asymptotic expansion in powers of the square root of ϵ, denoted by η, involving functions of y and of Y=y/η. This also yields Gevrey asymptotic expansions of the so-called Écalle-Voronin invariants of the equation which are functions of epsilon. An application coming from the theory of complex iteration is presented. On considère des équations aux différences dans le plan complexe de la forme y(x+ϵ)−y(x)=ϵf(y(x))/y(x). Le pas de discrétisation ϵ>0 est un petit paramètre, et l'équation a une singularité en y=0. On décrit les solutions près de la singularité en utilisant des développements asymptotiques combinés. Plus précisément, on montre que la dérivée v′ de la fonction réciproque (appelée coordonnée de Fatou) v d'une solution admet un développement asymptotique Gevrey en puissances de la racine carrée de ϵ, notée η, et faisant intervenir des fonctions de y et de Y=y/η. On obtient également des développements asymptotiques Gevrey des invariants d'Écalle-Voronin de l'équation, qui sont des fonctions de ϵ. Une application venant de la théorie de l'itération complexe est présentée.





1968 ◽  
Vol 70 (2) ◽  
pp. 123-129 ◽  
Author(s):  
P. R. Sharpe ◽  
J. B. Dent

SUMMARYTwo experiments designed to provide data for the estimation of functional relationships, which may be used to determine economically optimum plant populations and planting patterns in Desire'e potatoes, are described. Functional relationships between the number of main stems per acre and yield per acre were estimated from the results of experiment (i). Experiment (ii) investigated the relationship between stem number per tuber and seed tuber weight. ‘Square root’ functions estimated for seed yield and ware yield from the results of Exp. (i) were used to calculate a total Financial Returns curve. This returns curve, together with the Cobb-Douglas function estimated from the results of Exp. (ii), was used to calculate the stem numbers per acre, which would give maximum returns per acre and economically optimum returns in different cost/price situations.



1992 ◽  
Vol 139 (6) ◽  
pp. 505 ◽  
Author(s):  
S.E. McQuillan ◽  
J.V. McCanny
Keyword(s):  




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