UKismetMathLibrary::Vector_IsNAN

function Engine Blueprint Since 4.0

#include "Kismet/KismetMathLibrary.h"

Access: public Specifiers: staticUFUNCTIONBlueprintPure

Description

Returns true if any component of the vector is Not-a-Number (NaN). Primarily used for defensive validation of values arriving from physics, animation, or external data.

Caveats & Gotchas

• A NaN in any single component propagates to all subsequent arithmetic operations on the vector. Catching NaN early — especially before passing to physics or AI — prevents silent state corruption that is very hard to debug.
• This function only detects NaN, not Inf. Use FMath::IsFinite per-component if you also need to catch infinity values (e.g., from a divide-by-zero on a FVector component).

Signature

static UE_INL_API bool Vector_IsNAN(const FVector& A);

Parameters

Name	Type	Description	Default
A	FVector	The vector to test for NaN components.	—

Return Type

bool

Example

Validate physics output before applying to transform C++

FVector SimulatedVel = PhysicsBody->GetPhysicsLinearVelocity();
if (UKismetMathLibrary::Vector_IsNAN(SimulatedVel))
{
    UE_LOG(LogTemp, Error, TEXT("Physics velocity NaN detected — resetting"));
    PhysicsBody->SetPhysicsLinearVelocity(FVector::ZeroVector);
    return;
}
ApplyVelocity(SimulatedVel);

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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