# How to save the Jacobian matrix of the last Newton iteration?

**URL:** <https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500>\
**Category:** Perfect foresight simulations\
**Created:** [3 November 2026 10:37 UTC](https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500 "2026-11-03T10:37:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Vik1](https://forum.dynare.org/letter_avatar_proxy/v4/letter/v/e9c0ed/32.png) [@Vik1](https://forum.dynare.org/u/Vik1)\
**Post date:** [3 November 2026 10:37 UTC](https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500/1 "2026-11-03T10:37:27Z")

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How to save the final iteration of the Jacobian matrix A (or full(A)) in the file sim1.m?

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**Author:** ![jpfeifer](https://forum.dynare.org/user_avatar/forum.dynare.org/jpfeifer/32/5044_2.png) [@jpfeifer](https://forum.dynare.org/u/jpfeifer)\
**Post date:** [3 November 2026 15:43 UTC](https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500/2 "2026-11-03T15:43:41Z")

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There is no default way of doing this. But you can manually add a save command in `sim1` like

```auto
if converged
save('sim1_debug',A)
....

```

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<div class="post-metadata">

**Author:** ![Vik1](https://forum.dynare.org/letter_avatar_proxy/v4/letter/v/e9c0ed/32.png) [@Vik1](https://forum.dynare.org/u/Vik1)\
**Post date:** [3 November 2026 15:53 UTC](https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500/3 "2026-11-03T15:53:36Z")

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Thanks a lot. But new Dynare’s versions don’t allow for edditing sim1. I will try to do this with older versions.

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<div class="post-metadata">

**Author:** ![Vik1](https://forum.dynare.org/letter_avatar_proxy/v4/letter/v/e9c0ed/32.png) [@Vik1](https://forum.dynare.org/u/Vik1)\
**Post date:** [3 November 2026 16:00 UTC](https://forum.dynare.org/t/how-to-save-the-jacobian-matrix-of-the-last-newton-iteration/28500/4 "2026-11-03T16:00:21Z")

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(post deleted by author)