# Help calculating OSI?

**URL:** https://discourse.paraview.org/t/help-calculating-osi/13449
**Category:** ParaView Support
**Created:** [December 5, 2023, 5:51pm UTC](https://discourse.paraview.org/t/help-calculating-osi/13449 "2023-12-05T17:51:06Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![annap](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/41988e/32.png) [@annap](https://discourse.paraview.org/u/annap)
#### Post date: [December 5, 2023, 5:51pm UTC](https://discourse.paraview.org/t/help-calculating-osi/13449/1 "2023-12-05T17:51:06Z")

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Could someone please help me figure out how to calculate OSI? I have WSS vectors for every point for every timestep, and I need to find OSI (I believe scalars) over the cardiac cycle (0 to T) for every point. I can’t figure out how to calculate the time integrals. Any help would be greatly appreciated. Thank you!  
 ![image](https://discourse.paraview.org/uploads/default/original/2X/9/9f78d9fa8640becc1246f9d8739a8e36d5029676.png)

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### Author: ![chotirawee](https://discourse.paraview.org/user_avatar/discourse.paraview.org/chotirawee/32/9226_2.png) [@chotirawee](https://discourse.paraview.org/u/chotirawee)
#### Post date: [December 27, 2023, 3:09pm UTC](https://discourse.paraview.org/t/help-calculating-osi/13449/2 "2023-12-27T15:09:10Z")

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Hi,

I think the best way to do this is to realise that a time-integral over the cardiac cycle is equal to the time-average value multiplied by the time interval (T)

In other words, you can just replace those time-integrals with time-average values.

Hope this helps.