# DifferentialEquations.jl: LU factor ( M + dt \* K ) once prior to time-stepping loop
**URL:** https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255
**Category:** Modelling & Simulations
**Tags:** question
**Created:** [May 22, 2025, 8:59pm UTC](https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255 "2025-05-22T20:59:40Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@ziolai](https://discourse.julialang.org/u/ziolai)
#### Post date: [May 22, 2025, 8:59pm UTC](https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255/1 "2025-05-22T20:59:40Z")
Can once trick DifferentialEquations.jl to LU factor M + dt \* K once only prior to the time stepping loop? Thx.
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### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [May 22, 2025, 9:59pm UTC](https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255/2 "2025-05-22T21:59:19Z")
It already reuses the jacobian (and factorization) when possible.
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### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [May 23, 2025, 1:21am UTC](https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255/3 "2025-05-23T01:21:53Z")
When you solved, if you check `sol.stats`, how many times did it factorize?
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### Author:  [@ziolai](https://discourse.julialang.org/u/ziolai)
#### Post date: [May 23, 2025, 11:38am UTC](https://discourse.julialang.org/t/differentialequations-jl-lu-factor-m-dt-k-once-prior-to-time-stepping-loop/129255/4 "2025-05-23T11:38:18Z")
Many thanks for referring to sol.stats !
I am looking further into this further.