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matematica-financeira

Perform Brazilian financial calculations with decimal arithmetic and generate amortization tables.

1|Updated Mar 10, 2026
Search Tags:#decimal#brazil#interest#amortization#financial-calculations#vpl#tir
One-click install
npx skills add https://github.com/Moisesjr20/gueclaw --skill matematica-financeira
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: matematica-financeira
Source: https://github.com/Moisesjr20/gueclaw/tree/main/.agents/skills/matematica-financeira
Command: npx skills add https://github.com/Moisesjr20/gueclaw --skill matematica-financeira

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Deliver precise, auditable financial calculations and clear explanations for interest, amortization, discounts, investment viability metrics, and indexer adjustments used in Brazil, reducing manual errors and ambiguity in monetary flows and legal liquidations.

Core Features & Use Cases

  • Interest calculations: simple and compound interest with clear development and final amounts.
  • Amortization systems: full SAC and Price simulations with period-by-period tables and interpretations.
  • Investment analysis: VPL, TIR and payback (simple and discounted) with convergence criteria and warnings about multiple IRRs.
  • Discounts and conversions: commercial and rational discounts, rate equivalence (annual ↔ monthly ↔ daily using Brazil's 252 business-day basis).
  • Brazil-specific context: guidance on SELIC, CDI, IPCA, IGP-M conventions and judicial liquidation pitfalls (EC 113/2021, currency conversion, interest start dates).
  • Precision and reproducibility: enforces decimal arithmetic, banker's rounding (ROUND_HALF_EVEN), and offers Python Decimal code snippets for reproducible results.
  • Use case: simulate a mortgage amortization table, compare SAC vs Price by VP, or compute corrected judicial debt respecting currency history and legal marcos.

Quick Start

Calculate an SAC amortization table for R$100000 at 2% monthly over 4 months and provide the step-by-step math, final table, and a Python Decimal snippet demonstrating the computation.

Frequently Asked Questions about matematica-financeira

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I calculate an SAC amortization table for a Brazilian mortgage?▼

To calculate an SAC amortization table, provide the principal, monthly rate, and term. The system generates a period-by-period schedule with constant amortization and decreasing interest, plus a Python Decimal snippet for precision.

What is the difference between SAC and Price amortization systems?▼

SAC amortization features constant principal payments with decreasing installments, while Price amortization features fixed total installments. The system simulates both methods and compares them by present value to clarify monetary flow differences.

How do I convert annual interest rates to daily rates using the 252 business-day basis?▼

Rate conversion on the 252 business-day basis translates annual rates to daily or monthly equivalents using decimal arithmetic. You must supply the original rate and target period so the system can compute the exact equivalence under Brazilian conventions.

Can I calculate VPL and TIR with warnings for multiple internal rates of return?▼

Yes, VPL and TIR calculations include payback analysis with convergence criteria. The system actively warns about multiple IRR possibilities when cash flow signs change more than once, ensuring accurate investment viability metrics.

Does this handle judicial liquidation scenarios with SELIC, CDI, IPCA, and IGP-M indexers?▼

Yes, judicial liquidation calculations apply SELIC, CDI, IPCA, and IGP-M conventions including EC 113/2021 guidelines. You must supply current index values, currency history, and interest start dates to compute corrected legal debts accurately.

Why does my financial calculation have rounding errors in decimal monetary values?▼

Decimal rounding errors occur when using floating-point arithmetic instead of decimal precision. The system enforces banker's rounding (ROUND_HALF_EVEN) and uses decimal arithmetic to eliminate manual errors and ambiguity in monetary flows.

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