arXiv subjects

Yohanes Surya

Publications and source records attributed to Yohanes Surya.

10 recordsLinked to original sources

arXiv2025

A New Approach to Learn Trigonometry

We introduce the Primary Gasing Triangle, a right triangle with a hypotenuse of 1 unit, to define the primary trigonometric functions: sine and cosine. This triangle serves as the foundational element in a new approach to learning trigonometry, enabling us to derive the Derived Gasing Triangle, where the other four trigonometric functions (tangent, secant, cotangent, and cosecant) are defined. Using the Primary Gasing Triangle, we derive key trigonometric formulas, provide several proofs of the Pythagorean theorem using trigonometry, and solve various trigonometry problems. This approach makes learning trigonometry simpler, easier, and more intuitive.

math.HO↗

arXiv2005

What can we see from Investment Simulation based on Generalized (m,2)-Zipf law?

The paper revisits the investment simulation based on strategies exhibited by Generalized (m,2)-Zipf law to present an interesting characterization of the wildness in financial time series. The investigations of dominant strategies on each specific time series shows that longer words dominant in larger time scale exhibit shorter dominant ones in smaller time scale and vice versa. Moreover, denoting the term wildness based on persistence over short term trend and memory represented by particular length of words, we can see how wild historical fluctuations over time series data coped with the Zipf strategies.

physics.soc-ph↗

arXiv2004

Power Law Signature in Indonesian Population

The paper analyzes the spreading of population in Indonesia. The spreading of population in Indonesia is clustered in two regional terms, i.e.: kabupaten and kotamadya. It is interestingly found that the rank in all kabupaten respect to the population does not have fat tail properties, while in the other hand; there exists power-law signature in kotamadya. We analyzed that this fact could be caused by the equal or similar infrastructural development in all regions; nevertheless, we also note that the first 20 kabupatens are dominated in Java and Sumatera. Furthermore, the fat tail character in the rank of kotamadya could be caused by the big gap between big cities one another, e.g.: Jakarta, Surabaya, and others. The paper ends with some suggestions of more attention to infrastructural development in eastern regional cities.

nlin.PS↗

arXiv2004

Statistical Facts of Artificial Stock Market

The paper reports the construction of artificial stock market that emerges the similar statistical facts with real data in Indonesian stock market. We use the individual but dominant data, i.e.: PT TELKOM in hourly interval. The artificial stock market shows standard statistical facts, e.g.: volatility clustering, the excess kurtosis of the distribution of return, and the scaling properties with its breakdown in the crossover of Levy distribution to the Gaussian one. From this point, the artificial stock market will always be evaluated in order to have comprehension about market process in Indonesian stock market generally.

cond-mat.other↗

arXiv2004

Democracy: Order out of Chaos

We construct a majority cellular automata based model to explain the power-law signatures in Indonesian general election results. The understanding of second-order phase transitions between two different conditions inspires the model. The democracy is assumed as critical point between the two extreme socio-political situations of totalitarian and anarchistic social system - where democracy can fall into the twos. The model is in multi-party candidates system run for equilibrium or equilibria, and used to fit and analyze the three of democratic national elections in Indonesia, 1955, 1999, and 2004.

nlin.AO↗

arXiv2004

Neural Network Revisited: Perception on Modified Poincare Map of Financial Time Series Data

Artificial Neural Network Model for prediction of time-series data is revisited on analysis of the Indonesian stock-exchange data. We introduce the use of Multi-Layer Perceptron to percept the modified Poincare-map of the given financial time-series data. The modified Poincare-map is believed to become the pattern of the data that transforms the data in time-t versus the data in time-t+1 graphically. We built the Multi-Layer Perceptron to percept and demonstrate predicting the data on specific stock-exchange in Indonesia.

cond-mat.dis-nn↗

arXiv2004

Agent-based Model Construction In Financial Economic System

The paper gives picture of enrichment to economic and financial system analysis using agent-based models as a form of advanced study for financial economic data post-statistical-data analysis and micro-simulation analysis. Theoretical exploration is carried out by using comparisons of some usual financial economy system models frequently and popularly used in econophysics and computational finance. Primitive model, which consists of agent microsimulation with fundamentalist strategy, chartist, and noise, was established with an expectation of adjusting micro-simulation analysis upon stock market in Indonesia. The result of simulation showing how financial economy data resulted analysis using statistical tools such as data distribution and central limit theorem, and several other macro-financial analysis tools previously shown (Situngkir & Surya, 2003b). This paper is ended with several further possible advancements from the model built.

nlin.AO↗

arXiv2004

Stylized Statistical Facts of Indonesian Financial Data: Empirical Study of Several Stock Indexes in Indonesia

This paper is trying to unveil general statistical characteristic of financial; time series data that is subjected to several financial time series data present in Indonesia, e.g. individual index such as stock price of PT. TELKOM, stock price of PT HM SAMPOERNA, and compiled stock price index (Jakarta Stock Exchange Index). Characteristics that we try to analyze are volatility clustering, truncated Levy distribution, and multifractality feature. This analysis is directed for further works of research in making Indonesian artificial stock exchange that gives representation of micro structure of stock exchange in Indonesia. This paper is a resume of statistic behavior analyzed in top-down to become the ground in starting a more bottom-up analysis.

cond-mat.other↗

arXiv1999

The role of S_11 resonance in pi N Scattering

We analyze Pion Nucleon Scattering up to 700 MeV using a simple, relativistic, unitary model\cite{1}. The kernel of the integral equation includes nucleon, roper, delta, D_13 as well as S_11 poles with their corresponding crossed pole terms approximated by contact interactions. The s- and p- wave phase shifts are calculated from the model and shown to agree very well with the values derived from pi N scattering data \cite {2}. All parameters which involve S_{11} are presented.

nucl-th↗

arXiv1996

Two-pion exchange potential and the $πN$ amplitude

We discuss the two-pion exchange potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant $πN$ scattering amplitude which includes $Δ$, Roper, and $D_{13}$ isobars, as well as contact terms and off-shell (non-pole) dressed nucleon terms. The $πN$ amplitude satisfies chiral symmetry constraints and fits $πN$ data below $\sim$ 700 MeV pion energy. We find that this TPE potential can be well approximated by the exchange of an effective sigma and delta meson, with parameters close to the ones used in one-boson-exchange models that fit $NN$ data below the pion production threshold.

nucl-th↗