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Desimal: Jurnal Matematika
Published by Universitas Islam Negeri Raden Intan Lampung
ISSN : 26139073     EISSN : 26139081     DOI : -
Core Subject : Education, Social,
Education Mathematics Social Sciences
Desimal: Jurnal Matematika, particularly focuses on the main issues in the development of the sciences of mathematics education, mathematics education, and applied mathematics. Desimal: Jurnal Matematika published three times a year, the period from January to April, May to Augustus, and September to December. This publication is available online via open access.
Arjuna Subject : -
Articles 399 Documents
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Adversity Quotient and Students’ Mathematical Reasoning, Communication, and Connection Abilities: A PLS-SEM Analysis Destiani, Sinta; Rinaldi, Achi; Pitri, Rizka
Desimal: Jurnal Matematika Vol. 9 No. 2 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/djm.v9i2.31829

Abstract

Mathematical reasoning, communication, and connection are essential competencies for meaningful mathematics learning, yet their development may also depend on how students respond to academic difficulty. This study examined the structural relationships between Adversity Quotient (AQ) and students’ mathematical reasoning, communication, and connection abilities, including the direct and indirect pathways among these constructs. A quantitative cross-sectional design using Partial Least Squares Structural Equation Modeling (PLS-SEM) was employed with 106 seventh-grade students at SMPN 1 Natar, Lampung, Indonesia. Data were collected using an AQ questionnaire and a 15-item social-arithmetic test assessing mathematical reasoning, communication, and connection abilities, and were analyzed using SmartPLS 3.0. The results showed that AQ was positively associated with mathematical communication (β = 0.573, p < .001) but was not significantly associated with mathematical reasoning (β = -0.139, p = .183) or mathematical connection (β = -0.071, p = .399). Mathematical reasoning was positively associated with communication (β = 0.390, p < .001), while communication showed the strongest direct relationship with connection (β = 0.712, p < .001). Significant indirect effects were found for AQ on connection through communication (β = 0.408, p < .001) and for reasoning on connection through communication (β = 0.278, p < .001). These findings identify mathematical communication as a central structural bridge linking adversity-related responses and reasoning with students’ ability to establish mathematical connections, offering an integrated perspective on affective and cognitive processes in mathematics learning, particularly within lower-secondary mathematics education in Indonesia.
Optimization of Course Timetabling Using Spreadsheet-Based Integer Linear Programming with a Pedagogical Approach Zelimov, Katryn Monica; Utomo, Putranto Hadi; Kusmayadi, Tri Atmojo
Desimal: Jurnal Matematika Vol. 9 No. 2 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/djm.v9i2.32291

Abstract

University course timetabling is commonly evaluated through operational feasibility, while pedagogical considerations such as cognitive-demand distribution and class timing receive less explicit attention in optimization models. This study developed a spreadsheet-based Integer Linear Programming (ILP) model that integrates conventional hard constraints with pedagogically informed soft constraints to generate a feasible and more educationally responsive timetable. A mathematical modeling and computational simulation design was employed using synthetic data comprising five courses, four lecturers, two classrooms, five daily time slots, and two instructional days. The model incorporated classroom allocation, lecturer assignment and availability, room suitability and capacity, required course duration, and day-room consistency as hard constraints, while cognitive-demand distribution, post-lunch scheduling, and first-slot placement were treated as soft constraints. The formulation was implemented in Microsoft Excel and solved using OpenSolver with the COIN-OR CBC engine. The resulting timetable satisfied all hard constraints, confirming operational feasibility, while the three pedagogical penalty components produced values of 4, 0, and 1, respectively. These results indicate that excessive daily concentration of cognitively demanding courses could be fully avoided, although some temporal-placement penalties remained under the available scheduling conditions. The findings demonstrate that pedagogically informed preferences can be incorporated into an accessible ILP framework without compromising feasibility. This study therefore provides a transparent proof of concept for extending university timetabling beyond conflict avoidance toward multidimensional schedule quality that combines operational requirements with explicit cognitive and temporal considerations. The approach also preserves transparency for institutional inspection and adaptation.
Global Stability Analysis and Numerical Simulation of Water Pollutants Dispersion Model Using Lyapunov Function Asrotul Ula Desy Sa'idah, Nur; Irawati, Santi; Muksar, Makbul
Desimal: Jurnal Matematika Vol. 9 No. 2 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i2.32788

Abstract

Water pollution dynamics are shaped by interactions among contaminant states, yet many mathematical models do not explicitly distinguish how phase conversion influences long-term persistence. This study analyzes a five-compartment nonlinear model comprising available water, soluble pollutants, completely insoluble pollutants, semi-insoluble pollutants, and treated water. The objectives were to establish mathematical feasibility, characterize equilibrium states and pollutant-specific persistence thresholds, determine global asymptotic stability using Lyapunov functions, and examine temporal behavior numerically. Positivity and boundedness were analyzed to define an admissible region, thresholds were derived through the Next-Generation Matrix, and fourth-order Runge-Kutta simulations were performed over 0≤t≤100 using the baseline parameter configuration. The model admits a pollutant-free equilibrium and pollutant-persistent equilibria, while the threshold values were R1=40.0947, R2=2.6437, R3=1.9790, giving R0=40.0947. These values indicate that the soluble-pollutant pathway exerts the strongest persistence pressure under the baseline configuration. Lyapunov analysis identifies the stability conditions governing the relevant equilibria, and the numerical trajectories are consistent with persistence of the soluble compartment and decline of the completely insoluble and semi-insoluble compartments. One-at-a-time parameter perturbations further show that pollutant-transfer and recovery parameters alter peak magnitude, persistence duration, and convergence behavior. The study demonstrates that combining phase-resolved compartmental structure, pollutant-specific thresholds, global stability analysis, and numerical simulation provides an interpretable framework for explaining how pollutant heterogeneity and inter-phase conversion shape long-term water-pollution dynamics. This integration clarifies why different pollutant phases can follow distinct asymptotic pathways even when they coexist within the same modeled aquatic system over time.
Students’ Cognitive Processes in Solving Group Theory Problems: An Analysis Based on Bloom’s Taxonomy Wahyuni, Dewi Sri; Rochaminah, Sutji; Sartika, Nurhalida; Windra
Desimal: Jurnal Matematika Vol. 9 No. 2 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i2.30240

Abstract

Abstract algebra requires students to coordinate formal definitions, algebraic properties, and proof structures rather than rely on procedural recall alone. This study describes the cognitive processes demonstrated by fifth-semester mathematics education students when solving introductory group theory problems, using the first four categories of the revised Bloom’s taxonomy as an analytical lens. The study employed a qualitative descriptive approach at the Mathematics Education Study Programme, Alkhairaat University, from 15 September to 6 November 2025. Four students (LF, WS, AR, and N), selected purposively from students enrolled in the algebraic structures course, completed two written tasks and participated in interviews used to clarify their responses. The first task examined students’ definitions of a group, while the second required them to state and prove a theorem about group properties. All four students recalled central elements of the group definition, although the precision of their explanations varied. In the proof task, LF produced a coherent argument for the uniqueness of the identity element, whereas WS, AR, and N attempted to use familiar group properties but showed difficulties in theorem selection, property identification, or the logical ordering of operations. Across the four cases, remembering was consistently supported, whereas evidence of understanding was partial for several participants, and applying and analyzing were most clearly demonstrated in LF’s proof. These findings suggest that assessment of group theory learning should distinguish the recall of definitions and properties from the ability to coordinate them within a valid proof.
Casewise Spectral and Hamming-Weight Classification of Twisted Centralizer Codes from All-Ones Matrix Perturbations Temones, John Ben
Desimal: Jurnal Matematika Vol. 9 No. 3 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/

Abstract

Twisted centralizer codes determined by A = xJₙ + yIₙ are examined over a finite field F_q, with twist a ∈ F_q \ {0,1}. Previous universal claims of one-dimensionality for this family require qualification, particularly in modular characteristic. We establish a casewise dimension classification using the decomposition of the all-ones matrix when char(F_q) does not divide n and a nilpotent-operator argument when char(F_q) divides n. In the semisimple regime, the code dimension is governed by eigenvalue resonance; the one-dimensional full-weight MDS subfamily occurs when y + nx = 0, x ≠ 0, and char(F_q) does not divide n. Additional cases have dimension (n − 1)² or n − 1 with minimum distances 4 or 2n, respectively, under stated conditions. In the modular regime, x ≠ 0 and y = 0 yield dimension n² − 2n + 2; the minimum distance equals 4 for n ≥ 3 and 3 for n = 2, in which case a nontrivial [4,2,3] MDS code occurs. Explicit small-field examples check the derived parameters. The resulting distinctions correct overgeneralized spectral arguments and clarify the difference between extremal distance and information rate.
Dynamic Modeling and Stability Analysis of Loans, Deposits, and Liquidity in Conventional Banking Aulia, Lathifatul; Diana, Arista Fitri; Anggraini, Dyah Prita; Ginanjar, Agung
Desimal: Jurnal Matematika Vol. 9 No. 3 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i3.32376

Abstract

This study develops a three-dimensional nonlinear ordinary differential-equation model linking normalized deposits, loans, and liquidity through liquidity-dependent deposit pressure. The analysis derives the equilibrium conditions while retaining the regularization parameter, examines conditional positivity and boundedness, and evaluates local stability using the Jacobian and Routh–Hurwitz criterion. The nonnegative orthant is not generally forward invariant; therefore, global positivity is not claimed. For a literature-informed illustrative baseline, the model admits two positive interior equilibria. The lower equilibrium (D=0.165214, L=0.141010, R=0.047210) is unstable, whereas the upper equilibrium (D=0.999790, L=0.853321, R=0.285690) is locally asymptotically stable. The origin is also locally stable in the mathematical domain. Recalculated fourth-order Runge–Kutta simulations and ±5% one-at-a-time sensitivities show how the 50-year normalized indices respond to baseline parameters; deposit carrying capacity has the largest positive local sensitivity for deposits under the selected conditions. The numerical parameters are assumed or literature-informed rather than fitted to historical banking observations. Accordingly, the model offers a conditional theoretical account of nonlinear banking feedback and requires formal parameter estimation and external validation before operational or regulatory application.
Integer Labor Allocation to Maximize Coffee Harvest Output: A Branch and Bound Case Study Ambarsari, Ida Fitriana; Astindari, Tri; Hasanah, Nur; Irawati, Santi; Safitri, Emilia
Desimal: Jurnal Matematika Vol. 9 No. 3 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i3.32740

Abstract

Labor allocation is an important factor in coffee harvesting because differences in labor productivity, labor costs, working hours, and harvesting capacity can affect the effectiveness of resource utilization. This study aims to formulate and solve a mathematical optimization model for determining the optimal allocation of daily and contract labor to maximize coffee harvesting productivity at Mr Abdur’s coffee plantation. A quantitative mathematical optimization approach with a case study design was employed. Field data were collected through interviews and discussions with the plantation owner and included labor costs, working hours, harvesting capacity, and labor productivity. The problem was formulated as a Linear Programming model and first solved using the Simplex method as a continuous relaxation. Because the resulting decision variable was fractional. The model was subsequently solved as an Integer Linear Programming problem using the Branch and Bound method. The Simplex relaxation produced a continuous solution of approximately  and , with an objective value of approximately 450,72 kg. Since the number of workers must be an integer, Branch and Bound was applied and resulted in the optimal integer solution  and , yielding a maximum modeled productivity of 450 kf. This allocation requires 120 labor-hours and IDR 900.000 in labor expenditure, while its harvesting capacity reaches 3.120 trees, satisfying the available limits of 240 labor-hours, IDR 1.000.000, and 3.125 trees. The results demonstrate that the Simplex-Branch and Bound approach provides a mathematically feasible and operationally applicable solution for discrete labor allocation in coffee harvesting. The proposed model can support more systematic labor planning and resource allocation in smallholder coffee plantations.
A Non-Autonomous (Time-Varying) Lotka–Volterra Competition Model for Conventional and Islamic Banking Assets in Indonesia Rusdi, Wahyudi; Resmawan, Resmawan
Desimal: Jurnal Matematika Vol. 9 No. 3 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i3.32950

Abstract

This study examines the joint evolution of conventional and Islamic banking assets in Indonesia using a non-autonomous Lotka–Volterra competition model. The model was calibrated to a compiled annual series for 2016–2024 with time-dependent intrinsic growth and capacity terms, constrained nonlinear least squares, and adaptive Runge–Kutta integration. The working series includes two interpolated observations (2017–2018). For these inputs, the time-dependent model achieved in-sample MAPE of 1.52% for Islamic banking and 2.22% for conventional banking, while the fitted interaction coefficients were near zero under the imposed bounds. Nevertheless, the constant-parameter model had the lowest reported AICc, and five rolling-origin tests produced mean errors of 7.69% and 5.50%, respectively. Bootstrap and enlarged-bound analyses indicated weak identification of several growth and capacity parameters. Frozen-time Jacobian calculations yielded locally stable equilibria for the autonomous systems evaluated at the observed years, without establishing stability of the full non-autonomous system. A continuation to 2028 produced a conditional Islamic-market-share median near 7.2% and a reported 90% bootstrap interval of 6.4–9.2%. These outputs describe the behavior of the retained dataset and model assumptions rather than a causal effect of the 2021 BSI merger or a validated financial forecast. The results underscore the importance of complexity penalties, identifiability analysis, and source-data provenance in aggregate financial-dynamics modeling.
Design Thinking for Mathematical Critical Thinking in Digital Learning: A Systematic Literature Review Suharjito; Aryo Andri Nugroho; FX Didik Purwosetiyono
Desimal: Jurnal Matematika Vol. 9 No. 3 (2026): Desimal
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/desimal.v9i3.33155

Abstract

Mathematical critical thinking in digital learning requires purposeful interaction among pedagogical tasks, digital tools, and students' interpretation and justification of mathematical ideas. This systematic literature review examines the complementary functions of GeoGebra, Problem-Based Learning (PBL), Artificial Intelligence (AI), Meaningful Learning, and Design Thinking. The manuscript reports a qualitative thematic synthesis of 15 primary empirical studies published within the 2020–2026 search period and identified through Scopus, ERIC, Google Scholar, DOAJ, and Garuda. The available reporting record does not preserve complete database-specific retrieval and screening counts or item-level methodological appraisal results; the review therefore does not claim a fully reproducible PRISMA 2020 selection record. Across the cited evidence, GeoGebra provides dynamic mathematical representations; PBL structures problem-centred inquiry; AI offers feedback and alternative approaches that require mathematical verification; and Meaningful Learning emphasizes connections with prior knowledge. Design Thinking is proposed as a learner-centred organizing process through Empathize, Define, Ideate, Prototype, and Test. These differentiated functions support a conceptually coherent, potentially testable instructional pathway rather than a demonstrated effect of the combined intervention. Future research should verify the primary-study corpus, document review procedures in full, and test the proposed relationships in classroom settings.

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