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Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order.
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Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order.
det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg).A clearer path to an answer
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Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order.
Matrix entry a (row 1, column 1) · Matrix entry b (row 1, column 2) · Matrix entry c (row 1, column 3) · Matrix entry d (row 2, column 1) · Matrix entry e (row 2, column 2) · Matrix entry f (row 2, column 3) · Matrix entry g (row 3, column 1) · Matrix entry h (row 3, column 2) · Matrix entry i (row 3, column 3)
det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg).
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Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order.
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det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg).
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Formula: det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg).
Expand across the first row, compute three signed 2x2 minors, and combine them with the alternating plus-minus-plus cofactor signs. The result is one finite numeric determinant for the supplied 3x3 matrix.
Worked example: det([[1,2,3],[0,4,5],[1,0,6]]) = 1(24)-2(-5)+3(-4) = 22.
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Answer-first guide
Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order. Start with one clearly defined goal, enter values in the units shown, and keep the result attached to the assumptions below.
This tool is useful when your question includes 3x3 determinant, matrix determinant, cofactor expansion. It returns the outputs declared in the calculator contract rather than a live quote, approval, diagnosis, or professional sign-off.
Matrix entry a (row 1, column 1) · Matrix entry b (row 1, column 2) · Matrix entry c (row 1, column 3) · Matrix entry d (row 2, column 1) · Matrix entry e (row 2, column 2) · Matrix entry f (row 2, column 3) · Matrix entry g (row 3, column 1) · Matrix entry h (row 3, column 2) · Matrix entry i (row 3, column 3). Keep the same time period, unit system, and currency wherever the form requires comparable values.
Run the worked example first, compare its output with the page's example, then change one input at a time. This makes an unexpected result easier to trace to a unit, boundary, or assumption.
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det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg).
Expand across the first row, compute three signed 2x2 minors, and combine them with the alternating plus-minus-plus cofactor signs. The result is one finite numeric determinant for the supplied 3x3 matrix.
det([[1,2,3],[0,4,5],[1,0,6]]) = 1(24)-2(-5)+3(-4) = 22.
Context and background
Math calculators move from named quantities to a relation, then to a result that can be checked with substitution, units, or an alternate form.
Arithmetic, algebra, geometry, trigonometry, and number theory provide reusable structures for classroom work and everyday reasoning. Each page narrows that structure to one declared problem.
Research and review
Researched by Hassan ALRowaie, Founder and editorial researcher at WorldCalculate.
This guide follows the live calculator's declared inputs, formula, worked example, assumptions, validation boundaries, and source-backed methodology. The review date describes editorial review of the calculator explanation; it is not a promise that external facts or rates remain current.
A determinant compresses a square matrix into one scalar that depends on the arrangement of every entry. This calculator is deliberately bounded to a 3x3 numeric matrix written row by row. It expands along the first row, exposes the three 2x2 minors, and combines them with the alternating cofactor signs. The result can be positive, negative, or zero and is not automatically an inverse or a solution to a system. The guide explains the nine-field order, the expansion, a complete worked example, singular behavior, finite arithmetic, related matrix operations, source boundary, assumptions, and conservative limits. No symbolic matrix parser or hidden data table is used.
The page returns one scalar named the 3x3 determinant. It is computed from a square matrix whose entries are arranged in three rows and three columns. The output does not reproduce the matrix as a second object, although the steps identify its row-major structure and the three minors used in the expansion. A determinant can be zero without being an invalid calculation. Zero describes a singular case under ordinary linear algebra, while positive and negative values remain valid scalar outputs.
The determinant has different interpretations depending on the surrounding model. In a transformation setting, its absolute value can describe a volume scale and its sign can encode orientation. In a system of equations, a nonzero determinant can support uniqueness. This calculator does not choose one of those interpretations for the visitor. It performs the arithmetic and leaves units, transformation meaning, and any downstream decision in the documented problem context.
The first row is a, b, c, the second row is d, e, f, and the third row is g, h, i. The page labels each field with its row and column to reduce a common source of determinant errors: moving an entry to a nearby position. The example matrix is [[1,2,3],[0,4,5],[1,0,6]]. Entering the same nine numbers in a different layout is not a harmless reordering because the determinant belongs to the matrix positions, not merely to an unordered collection of values.
Every entry is a finite JavaScript number from negative one million through positive one million inclusive. Decimals, negative values, and zeros are valid. The bounds keep products and cofactor combinations within a predictable finite range for this page. They do not limit matrix mathematics in general. Direct handler calls are checked independently of the form, so strings that look numeric, blanks, NaN, infinity, and out-of-range values are rejected before any minor is formed.
Expanding across the first row gives det=a(ei-fh)-b(di-fg)+c(dh-eg). The first minor removes row one and column one, leaving [[e, f],[h, i]]. The second removes row one and column two, leaving [[d, f],[g, i]]. The third removes row one and column three, leaving [[d, e],[g, h]]. The signs are plus, minus, plus because cofactors alternate by position. Each 2x2 minor uses a diagonal product difference, not a sum.
The handler computes each minor as a finite intermediate result before multiplying it by the corresponding first-row entry. It then applies the signed combination and checks the determinant itself. This makes an intermediate overflow or a future bound change visible as a model-specific error rather than a nonfinite renderer value. It also gives the returned steps enough information for a human to compare the calculation with a written cofactor expansion.
Use the matrix [[1,2,3],[0,4,5],[1,0,6]]. The first minor is ei-fh=4*6-5*0=24. The second is di-fg=0*6-5*1=-5. The third is dh-eg=0*0-4*1=-4. Substitution into the expansion gives 1(24)-2(-5)+3(-4)=24+10-12=22. The calculator returns 22 as a finite scalar and shows the same three minor values in its steps.
A quick independent check can use row operations or a separate hand expansion, but the page does not implement those alternatives. The signs deserve attention: subtracting b times a negative minor adds 10 in this example. If the second term were written with a plus sign, the result would be 2 instead of 22. Keeping the matrix layout and each minor beside the final value makes that error easy to find.
A zero determinant is not an invalid input. It can occur when one row is a linear combination of the others, when rows are repeated, or in other arrangements that collapse the matrix's volume interpretation. The determinant operation still reports zero because no division is needed. A separate inverse operation would need a nonzero determinant, but that is outside this tool and should not be silently added to the meaning of the result.
Zero entries in individual positions do not predict the determinant by themselves. A matrix with several zeros can have a nonzero determinant, and a matrix with no zeros can have a zero determinant through cancellation. Signed entries likewise flow through ordinary multiplication and subtraction. At the numeric bounds, the products remain finite under the selected limits, but every derived minor and result is checked so the output contract remains explicit rather than relying on a rough magnitude assumption.
For a linear transformation of three-dimensional space, the absolute determinant is associated with the factor by which oriented volume changes, and the sign records whether orientation is preserved or reversed. That statement assumes the matrix is being used as a transformation in compatible coordinates. In another context, the determinant may simply be an algebraic denominator or a test for singularity. The calculator reports no volume unit because the fields have generic matrix units and the dimensional meaning cannot be inferred.
Scaling one row by a factor scales the determinant by that factor; scaling all three rows by the same factor scales it by the factor cubed. Swapping two rows changes the sign. These identities are useful mathematical checks. They also show why a determinant should not be compared across matrices whose units, row meanings, or normalization differ. A displayed rounded value may be fine for reading, but downstream matrix decisions should use the stored numeric result and a documented precision policy.
The result object contains one numeric entry, calculation steps, and a note that states the exact matrix order and the operation boundary. The numeric helper rejects nonfinite values and normalizes negative zero. The handler has no dynamic evaluation, no network access, and no dependency on a page object. A renderer can therefore format the scalar and steps without knowing how the matrix was entered. The underlying value is not rounded before return, so later code can choose its own display policy.
A 3x3 determinant is not a matrix inverse, trace, rank, eigenvalue, eigenvector, or system solution. Some of those operations use a determinant, but they have extra inputs, denominators, or interpretation rules. The existing 2x2 determinant/inverse tool is also distinct because its matrix size and operation menu differ. Keeping this page 3x3 determinant-only prevents a visitor from reading a valid scalar as evidence that a broader matrix workflow has completed.
The determinant reference stored with this record is private catalog metadata used by researchers to check the cofactor identity. The public article is original and does not reproduce an external page's prose, implementation, branding, defaults, or data. A formula reference does not choose whether a visitor's matrix is a physical transformation, a coefficient matrix, or a numerical test. That context must be supplied by the person using the result and recorded with the nine entries when it matters.
The model assumes a finite real 3x3 matrix in a shared row and column convention. It does not estimate condition numbers, quantify input error, or decide whether a small nonzero result is practically singular. It also does not attach physical dimensions to generic matrix units. For a high-consequence numerical workflow, use appropriate linear-algebra software, precision analysis, and review. This page is a transparent bounded arithmetic step, not a certificate of stability or invertibility.
Why does the determinant use a minus sign in the middle term? Cofactor signs alternate across a row, so the first-row pattern is plus, minus, plus. Why can the answer be negative? The signed products and row order determine the sign; negative is a valid real determinant. Why is a zero determinant allowed? The operation itself is defined at zero. Only a later operation that divides by the determinant, such as an inverse formula, would need an additional nonzero rule.
Can a determinant prove a real system has a unique solution? A nonzero coefficient determinant can be part of that conclusion for a correctly specified square linear system, but this page does not receive the right-hand side or verify the system model. Can it process a 4x4 matrix? No. The nine-field shape is deliberate. The conservative limit is one exact 3x3 determinant from finite numeric entries; larger matrices and broader conclusions require a different reviewed contract.
A determinant changes predictably under elementary row operations. Adding a multiple of one row to another leaves the determinant unchanged. Multiplying one row by a scalar multiplies the determinant by that scalar. Swapping two rows reverses the sign. These identities offer independent checks for a hand calculation and explain why row order matters. They are not extra operations implemented by this page; the handler evaluates the nine entered values exactly as placed in the row-major matrix.
A simple triangular matrix provides another check. The determinant of a triangular matrix is the product of its diagonal entries, because the off-diagonal terms do not contribute after the relevant cancellations. For a diagonal matrix with entries 2, 3, and 4, the result is 24. The calculator's cofactor expansion reaches the same value. Such examples help isolate the formula from the more visually complicated mixed-entry example and make a useful focused test fixture.
The first-row cofactors are not simply the three minors. The cofactor at position (1,1) has a positive sign, the one at (1,2) has a negative sign, and the one at (1,3) has a positive sign. The checkerboard pattern continues in a larger matrix, but this page needs only the first row of a 3x3. Writing each removed row and column beside its minor is a reliable way to avoid using d, e, f, g, h, or i in the wrong pair.
The expansion can be verified by choosing a different row or column, although the page intentionally fixes the first-row method for consistent steps. A correct determinant is independent of which expansion is used. If a different expansion disagrees, inspect the minor layout and the alternating sign before suspecting floating-point arithmetic. This is particularly important when a negative minor is multiplied by the middle negative cofactor, because two sign changes produce a positive contribution.
A determinant can be much smaller than the individual products that form it. In the worked matrix, the signed terms are 24, 10, and -12, which combine to 22. In a nearly dependent matrix, much larger terms can cancel to a small nonzero value. The calculator reports that arithmetic result but does not label a small determinant as practically singular. Numerical conditioning and a scale-relative tolerance depend on how the matrix was produced and what it will be used for.
The bounded entry range keeps the direct JavaScript operations finite for the intended page, but finite is not the same as exact. Products of large decimal entries can lose low-order bits, and a rounded display can hide a cancellation. Preserve the numeric result and matrix entries when reviewing a sensitive calculation. If the determinant is used to divide, invert, or certify a transformation, apply a domain-specific scale and precision analysis outside this simple handler.
The letters a through i are positional labels, not semantic names such as mass, price, or coordinate. In one problem the rows may represent equations; in another they may represent basis vectors or a transformation. The calculator cannot infer those meanings from the values. Store the matrix's row and column definitions with the result if it will be passed to another person or system. Otherwise a numerically correct determinant can be interpreted in the wrong domain.
The same caution applies to units. If rows and columns carry physical units, determinant dimensions may be a product of those units rather than a unitless scalar. This page uses generic matrix units and reports no physical dimension. A later transformation or volume calculation must declare its basis, coordinate scale, and orientation before giving the determinant an applied interpretation. The formula is reusable, but semantic labeling is not automatic.
A compact test set should include the catalog default, a diagonal matrix, a triangular matrix, a repeated-row singular matrix, negative entries, and values at the finite bounds. It should verify the numeric determinant and the three intermediate minors rather than only checking that an object was returned. It should also call the handler with strings, nonfinite values, and just-out-of-range entries to ensure direct callers receive clear Errors. These cases cover both algebraic branches and the renderer boundary.
The focused suite should inspect the exact row-major field order and the single `determinant` handler key. A generic robustness sweep can then perturb each field and check that every numeric value in the output tree is finite and serializable. This layered test strategy is stronger than a browser-only click because it catches a formula error before page markup, while the integrated registry test confirms that the same handler is actually reachable from the catalog route.
The page fixes expansion across the first row so every explanation uses the same sequence: a times the first minor, minus b times the second, plus c times the third. A different valid expansion can be useful as an independent check, but it should not be mixed halfway through a written calculation. Reproducibility depends on keeping the row-major mapping, minor definitions, and sign pattern together. The returned steps preserve that order for a human reviewer.
The same matrix values should produce the same scalar regardless of whether they arrive through the catalog defaults, a focused test, or the browser form. This is why the handler is pure and has no network or document dependency. It also means a caller can snapshot the nine inputs and the output for audit without capturing page state. The arithmetic remains bounded and deterministic under the declared JavaScript number contract.
The final scalar is meaningful only together with the matrix order and the operation that produced it. A value of 22 from the example is not a count of rows, a matrix norm, or a guarantee that an inverse is well conditioned. The determinant can be used as one ingredient in a larger theorem when the surrounding system meets that theorem's assumptions, but this record deliberately stops at the arithmetic expansion. The note and source metadata keep that stopping point visible.
For a durable handoff, store the nine entries in row-major order, the result, the numeric precision policy, and the context in which the matrix is used. If rows represent physical vectors, document their coordinate units and orientation. If they represent equation coefficients, document the unknown order. The same pure function can serve both settings because it does not guess semantics; the reviewer must supply them.
Calculate the determinant of a bounded finite numeric 3x3 matrix in row-major order.
det([[a,b,c],[d,e,f],[g,h,i]]) = a(ei-fh) - b(di-fg) + c(dh-eg). Expand across the first row, compute three signed 2x2 minors, and combine them with the alternating plus-minus-plus cofactor signs. The result is one finite numeric determinant for the supplied 3x3 matrix.
Enter Matrix entry a (row 1, column 1), Matrix entry b (row 1, column 2), Matrix entry c (row 1, column 3), Matrix entry d (row 2, column 1), Matrix entry e (row 2, column 2), Matrix entry f (row 2, column 3), Matrix entry g (row 3, column 1), Matrix entry h (row 3, column 2), Matrix entry i (row 3, column 3), then choose Calculate.
All nine entries are finite real numbers within the displayed bounds and are arranged row by row as [[a,b,c],[d,e,f],[g,h,i]]. The calculation returns the determinant only; it does not infer an inverse, rank, eigenvalues, or a linear-system solution. Ordinary JavaScript finite-number arithmetic is sufficient for the bounded entries, but display precision is not a claim about measurement accuracy.
This calculator is part of the WorldCalculate library. Its formula, example, assumptions, input bounds, and output formatting follow the official methodology.
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