LU Decomposition Calculator
Free LU decomposition calculator: Doolittle factors with verification. Instant, free, no sign-up.
Enter square A with nonzero pivots — get unit-lower L and upper U with the reconstruction error.
- Grade level
- 11–12 + College
- Curriculum band
- Difficulty
- Intermediate
- For this topic
- Time to master
- 2 weeks
- With daily practice
- Tools on page
- 10 on page
- Calculator + practice
Calculator
LU Decomposition (Doolittle)
LU Decomposition Calculator Summary
Breakdown
| Measure | Value |
|---|---|
| Determinant | L = [1, 0] [0.5, 1] |
| A | [2, 1] [1, 3] |
| L | [1, 0] [0.5, 1] |
| U | [2, 1] [0, 2.5] |
| recon error | 0 |
| size | 2 |
Substitution: Doolittle, no pivoting
Results
Determinant
L = [1, 0] [0.5, 1]
unit-diagonal L
[2, 1] [1, 3]
Detail value
[1, 0] [0.5, 1]
Detail value
[2, 1] [0, 2.5]
Detail value
0
Supporting value
2
Supporting value
Computed live from your inputs with guarded numeric methods; invalid or undefined cases report no value rather than a guess.
Statistics
Live readouts from your current inputs — charts and cards move together.
Determinant
L = [1, 0] [0.5, 1]
unit-diagonal L
A
[2, 1] [1, 3]
detail
L
[1, 0] [0.5, 1]
detail
recon error
0
support
Visualizations
Entries and components
Formula
LU banks the elimination work once: L records the multipliers, U is the triangular result — then systems solve in O(n²).
Alternative Form
Variables
| Symbol | Name | Unit | Description |
|---|---|---|---|
| mA | Matrix A | text | Rows with ; columns with , or space |
Explanation
[[2,1],[1,3]]: L = [[1,0],[0.5,1]], U = [[2,1],[0,2.5]].
Derivation
Elimination multipliers assemble L; U is the forward-pass output.
Step-by-Step Calculation
Follow each step to understand how the result is calculated from your inputs.
Read and validate the inputs.
Apply the defining operation.
Cross-check with an independent invariant.
State the finding.
Worked Examples
See how the calculator works with different scenarios.
Scenario
Clean split.
Inputs
Calculation
L factor
Result
[1, 0] [0.5, 1]
Interpretation
U = [[2,1],[0,2.5]].
Understanding Your Result
Your Result: A = L U
Typical range: Results scale with inputs; use the approach tables and cross-checks to confirm behavior at boundaries.
What This Means
The headline result is the LU Decomposition Calculator answer for your inputs, with supporting values alongside.
Why It Matters
LU Decomposition Calculator turns a multi-step procedure into one verified number you can trust in homework, exams and applied work.
Professional Interpretation
Report the headline with its check value; re-run at neighboring inputs to confirm stability.
Recommendations
- •Verify with the check row every time
- •Test a preset before your own numbers
- •Watch domains and asymptotes
Learn — The Complete Guide
The LU Decomposition Calculator evaluates linear algebra problems instantly and proves each answer with supporting values.
The core concept
Enter square A with nonzero pivots — get unit-lower L and upper U with the reconstruction error.
- Enter square A with nonzero pivots — get unit-lower L and upper U with the reconstruction error.
- Verify with the check row on every run.
- Domains and units decide validity.
Derivations — why the formulas work
Where the headline comes from
- 1Start from the defining relation
- 2Substitute the current inputs
- 3Simplify to the reported value
Where you meet this in real life
Learn this first — prerequisites in order
- 1Algebra: rearrange formulas
- 2Functions: read f(x) notation
- 3Linear Algebra: core vocabulary
Careers that use this daily
- •Engineer — models and verification
- •Scientist — data and curves
- •Teacher — worked examples
- •Analyst — quick computation
Why it helps
- •Instant verified answers
- •Steps that teach the method
- •Live charts that build intuition
Best practices
- •Estimate before computing
- •Verify with the inverse or check row
- •Re-run at a second point
Limitations — what this tool does not do
- •Numeric methods carry small rounding error
- •Inputs must satisfy stated domains
- •Display rounds to 9 significant digits
Curriculum map — where this topic lives in school
| Level | Grades | Standards | Skills |
|---|---|---|---|
| High school | 9–12 | HSF-TF, HSF-IF | Linear Algebra procedures · Verification habits |
| College | 13–14 | AP/IB standards | Numeric methods · Modeling |
Timeline — how this idea grew up
Ancient
Ratios and triangles
Early surveyors and astronomers tabulate chords and shadows.
1600s–1700s
Calculus formalized
Newton and Leibniz turn slopes and areas into computation.
1900s
Numeric methods
Calculators bring iteration to every classroom.
A little history
- • Tables of values predate calculators by millennia.
- • Modern pages pair closed forms with numeric checks.
Exam-day checklist
- • Write the formula first.
- • Verify with the check row.
- • Mind degrees vs radians.
- • Estimate before computing.
Myths vs facts
Practical Tips
- •Try a preset first
- •Read the steps panel once
- •Check the verdict line
- •Compare neighboring inputs
- •Copy the breakdown for notes
Common Mistakes
Assumptions
This calculator makes the following assumptions to provide estimates:
Limitations
Be aware of these limitations when using this calculator:
Frequently Asked Questions
Answers to common questions about this calculator.
Why factor instead of solving directly?
What if a pivot is zero?
How do I use this LU Decomposition Calculator?
What if my inputs are invalid?
Are the answers exact?
Related Calculators
Explore more calculators related to this topic.
Related Guides
Deepen your understanding with these educational resources.
Glossary
Technical terms used in mortgage calculations explained in plain language.
- LU factors
- L unit-lower, U upper.
- Doolittle
- Unit diagonal on L.
- Principal value
- The canonical output a calculator returns for a multi-valued inverse.
- Verification
- An independent recomputation (check row) that confirms the headline.
Authoritative References
Trusted sources and standards referenced by this calculator.
Applicable Standards
Diagrams & Illustrations
Visual intuition for every core idea. Select a card to enlarge it.
Did You Know?
Short intuition builders — great for class warm-ups.
Check rows are proofs
A check that recovers the input is a mini-proof your answer is right.
Presets teach patterns
Running 30-45-60 (or 0.1-0.01-0.001) reveals the structure instantly.
Estimate first
A rough mental answer catches 90% of entry errors.
Compare Side by Side
Headline answer with supporting values.
| Quantity | Value |
|---|---|
| Determinant | L = [1, 0] [0.5, 1] |
| A | [2, 1] [1, 3] |
| L | [1, 0] [0.5, 1] |
| recon error | 0 |
Recent Calculations
Your last runs on this page — stored only in this browser, never uploaded.
A = L U
Doolittle's method
Study Plan
A week-by-week path from prerequisites to mastery. Your checklist progress saves in this browser.
Prerequisites
- ▸Arithmetic and algebra fluency
- ▸Linear Algebra vocabulary
- ▸Function notation f(x)
Mastery progress — 0%
- I can set up LU Decomposition Calculator problems from words
- I can verify with the built-in checks
- I can explain why each step works
- I can spot invalid inputs
- 1
Week 1 · ~20 min/day
Core mechanics
Goals
- Run the worked examples on this page
- State each formula in words
- Verify every answer with the check row
Practice
Do 10 guided reps with the presets.
- 2
Week 2 · ~25 min/day
Fluency and speed
Goals
- Solve without the steps panel
- Explain each step aloud
- Mix in neighboring calculators
Practice
Timed sets of 5 mixed problems.
- 3
Week 3 · ~20 min/day
Apply and retain
Goals
- Model one real situation
- Teach the method to someone else
- Revisit after 3 days
Practice
One applied problem plus spaced review.
Exam tips
- •Write the formula before substituting.
- •Verify with the check row before moving on.
- •Track units and domains.
Practice Problems
0/4 solvedTry each problem first, peek at the hint only if stuck, then reveal the solution and mark it solved.
Run the first preset and state the answer in words.
Change one input and predict the direction of change.
Push an input toward a boundary or asymptote.
Model a real situation with these inputs.
Printable Worksheet
Generate a fresh problem set for class or homework. Print it, or copy the answer key separately.
- 1.18 × 47 =
- 2.8 ÷ 11 =
- 3.38 × 26 =
- 4.35 ÷ 4 =
- 5.21 − 16 =
- 6.2 + 26 =
- 7.14 ÷ 12 =
- 8.23 ÷ 3 =
- 9.49 ÷ 7 =
- 10.22 − 17 =
- 11.41 + 18 =
- 12.47 − 35 =
Formula Cheat Sheet
Every formula on this page in one printable table.
| Formula | Meaning | Example |
|---|---|---|
| L stores multipliers | Record | below diagonal |
| U is elimination out | Result | upper triangular |
| det = prod U diag | Bonus | L contributes 1s |
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Page Information
2026-09-29
3.1.0-math
Free to use for educational and professional purposes.