Ceiling function


The ceiling function is a function \(ceiling: \mathbb R \rightarrow \mathbb Z\) that rounds up a real number to the nearest integer. To be specific, \(ceiling(x)\), abbreviated as \(\lceil {x}\rceil \), returns the smallest integer \(y\) such that \(y \geq x.\) The ceiling function's counterpart is the floor function.

For example, \(\lceil {7.83}\rceil = 8\), \(\lceil {5}\rceil = 5\), \(\lceil {-2.2}\rceil = -2\) and \(\lceil {-9}\rceil = -9.\)

⚠ When the ceiling function is given an integer as its input, it returns the exact same integer as its output.
Logic & Proofs
IntegerRational numberInequalityReal numberTheoremProofStatementProof by exhaustionUniversal generalizationCounterexampleExistence proofExistential instantiationAxiomLogicTruthPropositionCompound propositionLogical operationLogical equivalenceTautologyContradictionLogic lawPredicateDomainQuantifierArgumentRule of inferenceLogical proofDirect proofProof by contrapositiveIrrational numberProof by contradictionProof by casesSummationDisjunctive normal form
Set Theory
SetElementEmpty setUniversal setSubsetPower setCartesian productStringBinary stringEmpty stringSet operationSet identitySet proof
Functions
FunctionFloor functionCeiling functionInverse function
Algorithms
AlgorithmPseudocodeCommandAsymptotic notationTime complexityAtomic operationBrute-force algorithm
Relations
RelationReflexive relationSymmetric relationTransitive relationRelation compositionEquivalence relationEquivalence class
Number Theory
Integer divisionLinear combinationDivision algorithmModular arithmeticPrime factorizationGreatest common divisorLeast common multiplePrimality testFactoring algorithmEuclid's theoremPrime number theoremEuclidean algorithm
Induction
Proof by inductionFibonacci sequenceProof by strong inductionWell-ordering principleSequenceFactorialRecursive definition
Combinatorics
Rule of productRule of sumBijection rulePermutationCombinationComplement ruleExperimentOutcomeSample spaceEventProbabilityProbability distributionUniform distributionMultisetSixfold wayInclusion-exclusion principlePigeonhole principle
Graph Theory
GraphWalkSubgraphRegular graphComplete graphEmpty graphCycle graphHypercube graphBipartite graphComponentEulerian circuitEulerian trailHamiltonian cycleHamiltonian pathTreeHuffman treeSubstringForestPath graphStarSpanning treeWeighted graphMinimum spanning treeGreedy algorithmPrim's algorithm
Recursion
RecursionRecursive algorithmCorrectness proofDivide-and-conquer algorithmSorting algorithmMerge sort