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INDONESIA
JURNAL MATEMATIKA STATISTIKA DAN KOMPUTASI
Published by Universitas Hasanuddin
ISSN : 18581382     EISSN : 26148811     DOI : -
Core Subject : Education,
Mathematics
Jurnal ini mempublikasikan paper-paper original hasil-hasil penelitian dibidang Matematika, Statistika dan Komputasi Matematika.
Arjuna Subject : -
Articles 534 Documents
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Hopf Bifurcation in an S–I–P Dynamic Model with Disease in the Prey Population and Holling Type III Functional Response : Bifurkasi Hopf pada Model Dinamik S-I-P GESTI ESSA WALDHANI WALDHANI
Jurnal Matematika, Statistika dan Komputasi Vol. 23 No. 1 (2026): September 2026
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/3c7xp937

Abstract

In this paper, a dynamic S-I-P model with disease in the prey population and Holling type III functional response with time-delay were discussed. Model analysis is carried out by determining fixed points, then analyzing the stability of the fixed points and discussing the existence of the Hopf bifurcation. Another modification given to the model is the use of time delays. Delay time is the time needed for a disease to make prey sick (incubation time). The first case is a model without time delay, it is obtained that 3 fixed points are unstable and 2 fixed points are stable. One of them is the interior fixed point tested with the Routh-Hurwitz criteria. The second case is a model with a delay time, the critical delay value is obained. Hopf bifurcation occurs when the delay time value is equal to the critical delay value and also fulfills the transversality condition. Observations on the model simulation are carried out by varying the value of the delay time. When the Hopf bifurcation occurs, the graph on the solution plane shows a constant oscillatory movement. If the value of the delay time given is less than the critical value of the delay, the system solution goes to a balanced state. Then when the delay time value is greater than the critical delay value, the system solution continues to fluctuate causing an unstable system condition.
Spectral Energy-Based Adaptive Homomorphic Filtering for Astronomical Image Enhancement Ahmad Fawaid Ridwan; Iqbal Robiyana
Jurnal Matematika, Statistika dan Komputasi Vol. 23 No. 1 (2026): September 2026
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/bfpvzv53

Abstract

Astronomical images often suffer from low contrast, uneven illumination, dark backgrounds, and sensor-induced noise, which can obscure faint celestial structures and reduce the effectiveness of subsequent image analysis. Conventional homomorphic filtering can improve illumination and contrast by attenuating low-frequency components and enhancing high-frequency details, but its use of a fixed cutoff frequency limits its adaptability to images with different spectral characteristics. This study proposes a Spectral Energy-Based Adaptive Homomorphic Filtering (SEAHF) method that estimates the cutoff frequency from the spectral energy ratio between low- and high-frequency components of each input image. The proposed mechanism modifies only the cutoff frequency while retaining the conventional Gaussian homomorphic filtering framework and fixed remaining filter parameters. The method was evaluated on 60 astronomical images from the SDSS, DECaLS, and Pan-STARRS surveys, selected from common sky coordinates available across the three sources, and compared with Contrast Limited Adaptive Histogram Equalization (CLAHE), Conventional Homomorphic Filtering (CHF), and Low-Light Image Enhancement via Illumination Map Estimation (LIME). Performance was evaluated using Structural Similarity Index Measure (SSIM), entropy, Lightness Order Error (LOE), and processing time. SEAHF consistently achieved the lowest LOE across the three datasets, with an overall LOE of 532570.5, while obtaining competitive SSIM (0.5714), entropy (6.0646), and processing time (0.009374 s). Although CLAHE and CHF achieved higher SSIM and CLAHE required less processing time, SEAHF provided the strongest illumination-order preservation while maintaining computational cost comparable to CHF. The results provide initial empirical evidence that spectral-energy-based adaptive cutoff estimation can improve illumination-order preservation while maintaining competitive structural similarity and computational cost.
A Comparative Analysis of the Accuracy of the Value at Risk Estimation Methods on Indonesian Banking Stocks Jusmawati Massalesse; Cindy Cindy
Jurnal Matematika, Statistika dan Komputasi Vol. 23 No. 1 (2026): September 2026
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/a1t1yd15

Abstract

Risk measurement is an important aspect in investment decision-making in the capital market. This study aims to compare the performance of three Value at Risk methods, namely Variance–Covariance, Historical Simulation, and Monte Carlo Simulation, in estimating investment risk in the shares of  PT. Bank Negara Indonesia (Persero) Tbk. (BBNI.JK), and PT. Bank Rakyat Indonesia (Persero) Tbk. (BBRI.JK). The study used daily closing price data for the period April 30, 2024, to April 30, 2025, were analyzed through return calculation, Kolmogorov–Smirnov normality test, VaR estimation at a confidence level of 95%, and model validation using Kupiec Backtesting. The results of the study showed that the three methods produced relatively consistent VaR estimates, with the VaR value of BBNI.JK shares being greater than BBRI.JK, which indicates a higher level of investment risk. The results of backtesting show that all methods meet the validity criteria and are therefore suitable for use in risk measurement. This study shows that the selection of the Value at Risk method needs to be adjusted to the characteristics of the return distribution and the objectives of risk analysis.
Fuzzy Ideal and Fuzzy Filter on Ordered Groupoid Aminah Muliawati; Saman Abdurrahman; Thresye Thresye
Jurnal Matematika, Statistika dan Komputasi Vol. 23 No. 1 (2026): September 2026
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/912h0e65

Abstract

Within fuzzy set theory, every element of nonempty set is assigned membership degree in interval [0, 1]. With development of fuzzy set theory, its concepts have been extended to algebraic structures, including ordered groupoids, leading to investigation of fuzzy ideals and fuzzy filters. This research investigates properties of fuzzy ideals together with their correspondence to classical ideals through fuzzy membership functions. It also studies the characteristics of fuzzy filters and their connection with fuzzy prime ideals. This research uses literature review to examine relationship between classical ideals and fuzzy ideals in ordered groupoids and by proving conditions for fuzzy subset to be a fuzzy ideal. Analysis also includes the characterization of fuzzy filters and their relation to fuzzy prime ideals through concept of fuzzy subset complements. The findings reveal that the characteristic function induced by a nonempty subset forms a fuzzy ideal precisely when the subset itself is an ideal of the ordered groupoid. Therefore, fuzzy ideals provide a natural generalization of classical ideals while maintaining the ordering relation and binary operation defined on an ordered groupoid.

Page 54 of 54 | Total Record : 534

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