scholarly journals On Koenigs' ratios for iterates of real functions

1969 ◽  
Vol 10 (1-2) ◽  
pp. 207-213 ◽  
Author(s):  
E. Seneta
Keyword(s):  
Functional Equation ◽  
General Result ◽  
Real Function ◽  
Real Solutions ◽  
Real Functions ◽  
Image Position ◽  
Schröder Functional Equation

In a recent note, M. Kuczama [5] has obtained a general result concerning real solutions φ(x) on the interval 0 ≦ x < a ≦∞ of the Schröder functional equation providing the known real function satisfies the following (quite weak) conditions: f(x) is continuous and strictly increasing in ([0 a);(0) = 0 and 0 <f(x) <x for x ∈ (0, a); limx→0+ {f(x)/x} = s; and f(x)/x is monotonic in (0, a).

Continuous Solutions of the Functional Equation fn(x) = f(x)

1953 ◽  
Vol 5 ◽  
pp. 101-103 ◽  
Author(s):  
G. M. Ewing ◽  
W. R. Utz
Keyword(s):  
Functional Equation ◽  
Real Axis ◽  
Continuous Solutions ◽  
The Real ◽  
Real Functions ◽  
Image Position

In this note the authors find all continuous real functions defined on the real axis and such that for an integer n > 2, and for each x,

scholarly journals ON SOME PEXIDER-TYPE FUNCTIONAL EQUATIONS CONNECTED WITH THE ABSOLUTE VALUE OF ADDITIVE FUNCTIONS. PART II

2012 ◽  
Vol 85 (2) ◽  
pp. 202-216 ◽  
Author(s):  
BARBARA PRZEBIERACZ
Keyword(s):  
Functional Equation ◽  
Abelian Group ◽  
Functional Equations ◽  
Additive Functions ◽  
Absolute Value ◽  
Real Functions ◽  
The Absolute ◽  
Image Position

AbstractWe investigate the Pexider-type functional equation where f, g, h are real functions defined on an abelian group G. We solve this equation under the assumptions G=ℝ and f is continuous.

scholarly journals ON SOME PEXIDER-TYPE FUNCTIONAL EQUATIONS CONNECTED WITH THE ABSOLUTE VALUE OF ADDITIVE FUNCTIONS. PART I

2012 ◽  
Vol 85 (2) ◽  
pp. 191-201 ◽  
Author(s):  
BARBARA PRZEBIERACZ
Keyword(s):  
Functional Equation ◽  
Abelian Group ◽  
Functional Equations ◽  
Additive Functions ◽  
Absolute Value ◽  
Real Functions ◽  
The Absolute ◽  
Image Position

AbstractWe investigate the Pexider-type functional equation where f,g,h are real functions defined on an abelian group G.

scholarly journals Arithmetic properties of certain functions in several variables III

1977 ◽  
Vol 16 (1) ◽  
pp. 15-47 ◽  
Author(s):  
J.H. Loxton ◽  
A.J. van der Poorten
Keyword(s):  
Functional Equation ◽  
General Result ◽  
Irrational Number ◽  
Arithmetic Properties ◽  
Several Variables ◽  
Image Position

We obtain a general transcendence theorem for the solutions of a certain type of functional equation. A particular and striking consequence of the general result is that, for any irrational number w, the functiontakes transcendental values at all algebraic points α with 0 < |α| < 1.

3. Laboratory Notes by Professor Tait (a.) Measurement of the Potential, required to produce Sparks of various lengths, in Air at different pressures, by a Holtz Machine

1878 ◽  
Vol 9 ◽  
pp. 332-333
Author(s):  
Messrs Macfarlane ◽  
Paton
Keyword(s):  
General Result ◽  
The Other ◽  
Considerable Distance ◽  
Image Position

The general result of these strictly preliminary experiments appears to show that for sparks not exceeding a decimetre in length (L), taken in air at different pressures (P), between two metal balls of 7mm·5 radius, the requisite potential (V), is expressed by the formulaThe Holtz machine employed is a double one, made by Ruhmkorff, and it was used with its small Leyden jars attached. The measurements had to be made with a divided-ring electrometer, so that two insulated balls, at a considerable distance from one another, were connected, one with the machine, the other with the electrometer.

scholarly journals Minimal theta functions

1988 ◽  
Vol 30 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Hugh L. Montgomery
Keyword(s):  
Functional Equation ◽  
Quadratic Form ◽  
Zeta Function ◽  
Theta Functions ◽  
Binary Quadratic Form ◽  
Positive Definite ◽  
Epstein Zeta Function ◽  
Image Position

Let be a positive definite binary quadratic form with real coefficients and discriminant b2 − 4ac = −1.Among such forms, let . The Epstein zeta function of f is denned to beRankin [7], Cassels [1], Ennola [5], and Diananda [4] between them proved that for every real s > 0,We prove a corresponding result for theta functions. For real α > 0, letThis function satisfies the functional equation(This may be proved by using the formula (4) below, and then twice applying the identity (8).)

scholarly journals The Bi-dimensional space of Korenblum and composition operator

2015 ◽  
Vol 62 (1) ◽  
pp. 1-12
Author(s):  
José A. Guerrero ◽  
Nelson Merentes ◽  
José L. Sánchez
Keyword(s):  
Banach Space ◽  
Composition Operator ◽  
Real Function ◽  
Dimensional Space ◽  
Similar Type ◽  
Functions Of Two Variables ◽  
Real Functions ◽  
Uniformly Continuous ◽  
Uniformly Bounded

Abstract In this paper we present the concept of total κ-variation in the sense of Hardy-Vitali-Korenblum for a real function defined in the rectangle Iab⊂R2. We show that the space κBV(Iab, R) of real functions of two variables with finite total κ-variation is a Banach space endowed with the norm ||f||κ = |f (a)| + κTV( f, Iab). Also, we characterize the Nemytskij composition operator H that maps the space of functions of two real variables of bounded κ-variation κBV(Iab, R) into another space of a similar type and is uniformly bounded (or Lipschitzian or uniformly continuous).

-SPHERICAL FUNCTIONS ON ABELIAN SEMIGROUPS

2017 ◽  
Vol 96 (3) ◽  
pp. 479-486 ◽  
Author(s):  
RADOSŁAW ŁUKASIK
Keyword(s):  
Functional Equation ◽  
Automorphism Group ◽  
Spherical Functions ◽  
Abelian Semigroup ◽  
Image Position

We present the form of the solutions $f:S\rightarrow \mathbb{C}$ of the functional equation $$\begin{eqnarray}\mathop{\sum }_{\unicode[STIX]{x1D706}\in K}f(x+\unicode[STIX]{x1D706}y)=|K|f(x)f(y)\quad \text{for }x,y\in S,\end{eqnarray}$$ where $f$ satisfies the condition $f(\sum _{\unicode[STIX]{x1D706}\in K}\unicode[STIX]{x1D706}x)\neq 0$ for all $x\in S$, $(S,+)$ is an abelian semigroup and $K$ is a subgroup of the automorphism group of $S$.

ON THE HYPERSTABILITY OF A PEXIDERISED -QUADRATIC FUNCTIONAL EQUATION ON SEMIGROUPS

2018 ◽  
Vol 97 (3) ◽  
pp. 459-470 ◽  
Author(s):  
IZ-IDDINE EL-FASSI ◽  
JANUSZ BRZDĘK
Keyword(s):  
Functional Equation ◽  
Commutative Semigroup ◽  
Quadratic Functional Equation ◽  
Inner Product ◽  
Quadratic Functional ◽  
Ulam Stability ◽  
Product Spaces ◽  
Inner Product Spaces ◽  
Image Position

Motivated by the notion of Ulam stability, we investigate some inequalities connected with the functional equation $$\begin{eqnarray}f(xy)+f(x\unicode[STIX]{x1D70E}(y))=2f(x)+h(y),\quad x,y\in G,\end{eqnarray}$$ for functions $f$ and $h$ mapping a semigroup $(G,\cdot )$ into a commutative semigroup $(E,+)$, where the map $\unicode[STIX]{x1D70E}:G\rightarrow G$ is an endomorphism of $G$ with $\unicode[STIX]{x1D70E}(\unicode[STIX]{x1D70E}(x))=x$ for all $x\in G$. We derive from these results some characterisations of inner product spaces. We also obtain a description of solutions to the equation and hyperstability results for the $\unicode[STIX]{x1D70E}$-quadratic and $\unicode[STIX]{x1D70E}$-Drygas equations.

An Analogue of the Wave Equation and Certain Related Functional Equations

1969 ◽  
Vol 12 (6) ◽  
pp. 837-846 ◽  
Author(s):  
John A. Baker
Keyword(s):  
Functional Equation ◽  
Wave Equation ◽  
Functional Equations ◽  
Geometric Interpretation ◽  
Continuous Solutions ◽  
Difference Analogue ◽  
Image Position

Consider the functional equation(1)assumed valid for all real x, y and h. Notice that (1) can be written(2)a difference analogue of the wave equation, if we interpret etc., (i. e. symmetric h differences), and that (1) has an interesting geometric interpretation. The continuous solutions of (1) were found by Sakovič [5].

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