A worked example
(5,1,4)−(2,3,−1)=(3,−2,5).
What the formula is measuring
The difference a−b is the displacement from b to a when both are position vectors. Vector Subtraction can be compared with difference length.
The roles assigned to vector a and vector b explain the operation that produces vector difference.
Reproducing the answer
Subtract matching components in the stated order.
Mistakes worth catching
Reversing the operands negates the result and reverses its geometric direction.
A rough estimate made before calculating gives the finished vector difference a useful plausibility check.
Problems this can answer
It finds coordinate changes, errors, relative velocity, and separation vectors.
Interpreting changes in the inputs
Treat each labeled field as part of the definition, not merely an empty box. The field assignment determines what the displayed vector difference describes. Convert measured values to compatible units first and retain their original precision until the final rounding choice.
Moving b toward a reduces the distance represented by the difference. Predict that movement before recalculating the vector difference; disagreement points to an input-role or sign issue.
Report the vector difference at a precision justified by the inputs. A long browser decimal is computational detail, not evidence that the source values were measured that accurately. When an exact symbolic form is conventional, keep it beside the rounded value so later work is not forced to reuse an early approximation.
Vector distance takes the magnitude of this difference. Here the requested quantity is specifically vector difference.
Keep the supplied inputs with the result, including any units and the final rounding place. The displayed formula then preserves how the vector difference was obtained.
Adding the subtrahend back
Vector Subtraction uses Vector a, and Vector b. Add vector b to the reported difference. The reconstruction should equal vector a in every component. Reversing the operands should negate every component of the difference.
For Vector Subtraction, retain component order, coordinate basis, and physical unit with the output. Adding the reported difference back to vector b should reconstruct vector a exactly before rounding.