Reference library
Foundations
Explore concepts, laws, equations and methods, with clear explanations of their use and sources. Choose an area of study or find a specific entry.
More filters
Reference entries
Showing 1501–1530 of 1709 reference entries
Planetary circulation couples radiation and dynamics; comparing advective, radiative and rotation time scales organizes possible regimes.
MethodEarth & cosmosSurvey selection in observed and intrinsic coordinatesA survey's detected density is the underlying observable distribution multiplied by a selection probability.
MethodEarth & cosmosActual 3D inversion: synthetic secret-model comparisonsThe Dublin Secret Model 1 benchmark compares three actual 3D magnetotelluric reconstructions of a spiral conductor from synthetic impedance data.
MethodEarth & cosmosQAMT 2025: synthetic recovery and a field applicationSchiffler and colleagues validate a 3D EM inversion implementation using five synthetic anomalies and compare recovered structures across survey observables.
MethodEarth & cosmosDark-sector models: compare evidence at each scaleGR with cold dark matter is the established cosmological comparison baseline.
MethodEarth & cosmosAcceleration models: fit and independent gravity testsA constant Λ is the minimal GR acceleration baseline; dynamical fields require additional assumptions and parameters.
MethodEarth & cosmosRadiation–matter exchange in relativistic accretionRadiation-GRMHD couples the matter-plus-magnetic stress tensor to a radiation tensor with opposite four-force sources, so their sum is covariantly conserved.
MethodMathematics & logicReal-number arithmetic lawsReal arithmetic permits regrouping, distributing and taking nonzero reciprocals.
Mathematical statementMathematics & logicFinite decimal place valueA decimal digit's position determines its power-of-ten weight.
DefinitionMathematics & logicRational numbers and recurring decimalsTerminating or eventually recurring decimals represent exactly the rational numbers.
Mathematical statementMathematics & logicArithmetic with fractionsFraction arithmetic preserves value by using common denominators or reciprocals.
MethodMathematics & logicAbsolute value and distance intervalsAbsolute value measures distance from zero on the real line.
DefinitionMathematics & logicPercent and relative changeA percentage states a ratio per hundred and needs an explicit base.
MethodMathematics & logicOrder rules for real inequalitiesScaling an inequality depends on the factor's sign.
Mathematical statementMathematics & logicInteger powers and positive-base rational powersNegative exponents use reciprocals; rational exponents use principal roots.
DefinitionMathematics & logicReal logarithms and their lawsA logarithm is the inverse of exponentiation for an admissible positive base.
DefinitionMathematics & logicQuadratic formula and discriminantThe discriminant classifies the real solutions of a quadratic equation.
Mathematical statementMathematics & logicFunction composition and inversesComposition feeds one output into another function; inversion requires unique preimages.
DefinitionMathematics & logicEuclidean triangle congruence testsSpecified matching sides and angles can establish the same triangle shape and size.
Mathematical statementMathematics & logicEuclidean triangle similarity testsTriangle similarity keeps corresponding angles and one common positive side scale.
Mathematical statementMathematics & logicAcute-angle right-triangle ratiosOpposite and adjacent legs depend on the chosen acute angle.
DefinitionMathematics & logicRadian angle, circular arc and sectorRadian measure is arc length divided by radius.
DefinitionMathematics & logicPlane area and perimeter formulasArea measures covered surface; perimeter measures boundary length.
Mathematical statementMathematics & logicRight-prism and cylinder volumesVolume and surface area measure different aspects of a solid.
Mathematical statementMathematics & logicDescriptive sample center and spreadMean, median, mode and sample variance summarize observed values.
MethodInformationTwo's-complement signed integersA signed interpretation assigns a negative weight to the highest bit.
DefinitionInformationOctets and multi-byte orderByte order describes the significance assigned to successive stored octets.
DefinitionInformationUnicode scalar values and UTF-8UTF-8 encodes scalar values with a variable number of octets.
DefinitionInformationText boundaries and Unicode normalizationText equality and character counts depend on the declared representation and convention.
MethodInformationIP addresses and datagram deliveryIP addresses identify network destinations; IP does not guarantee delivery.
Definition