question: protected void sanityChecks ( final ODEState initialState , final double t ) throws MathIllegalArgumentException { final double threshold = 1000 * FastMath . ulp ( FastMath . max ( FastMath . abs ( initialState . getTime ( ) ) , FastMath . abs ( t ) ) ) ; final double dt = FastMath . abs ( initialState . getTime ( ) - t ) ; if ( dt <= threshold ) { throw new MathIllegalArgumentException ( LocalizedODEFormats . TOO_SMALL_INTEGRATION_INTERVAL , dt , threshold , false ) ; } }
target:  Check the integration span.