# Unit step response

**URL:** <https://community.wolfram.com/t/unit-step-response/16572>\
**Category:** Questions\
**Tags:** control-systems\
**Created:** [August 14, 2020, 12:55pm UTC](https://community.wolfram.com/t/unit-step-response/16572 "2020-08-14T12:55:03Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![luiarboleda](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/luiarboleda/32/36674_2.png) [@luiarboleda](https://community.wolfram.com/u/luiarboleda)\
**Post date:** [August 14, 2020, 12:55pm UTC](https://community.wolfram.com/t/unit-step-response/16572/1 "2020-08-14T12:55:03Z")

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Hi  
If I have this transfer function :

```
sys1=(-1.27813*10^-6-25.4s)/(-5.008-25.1026s-50325s^2-s^3)*1/s

```

¿How can I find the unit step response?

I tried as follows :

```
y1 = OutputResponse[TransferFunctionModel[sys1, s], UnitStep, {t,0,5}]
  ListPlot[y1,{t,0,5}]

```

I find this case in OGATA’s book : Solving problems in Control Engineering with Matlab

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**Author:** ![rohitnamjoshi](https://avatars.discourse-cdn.com/v4/letter/r/f1d935/32.png) [@rohitnamjoshi](https://community.wolfram.com/u/rohitnamjoshi)\
**Post date:** [August 14, 2020, 1:51pm UTC](https://community.wolfram.com/t/unit-step-response/16572/2 "2020-08-14T13:51:25Z")

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Hi Luis,

You need to use `UnitStep[t]`, not `UnitStep`

```
y1 = OutputResponse[TransferFunctionModel[sys1, s], UnitStep[t], {t, 0, 5}]
Plot[y1, {t, 0, 5}]

```

I think you need to increase the range of `t` to see anything interesting.

```
y1 = OutputResponse[TransferFunctionModel[sys1, s], UnitStep[t], {t, 0, 10000}]
Plot[y1, {t, 0, 10000}]

```

 ![10439plot.png](https://global.discourse-cdn.com/wolfram/original/3X/c/d/cd92b0fa6d7b5e5086f94ef9fb6ad8a3ac2e236d.png)

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<div class="post-metadata">

**Author:** ![luiarboleda](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/luiarboleda/32/36674_2.png) [@luiarboleda](https://community.wolfram.com/u/luiarboleda)\
**Post date:** [August 15, 2020, 3:08pm UTC](https://community.wolfram.com/t/unit-step-response/16572/3 "2020-08-15T15:08:26Z")

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Thank you Rohit.

Great.

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<div class="post-metadata">

**Author:** ![btimofte](https://avatars.discourse-cdn.com/v4/letter/b/cab0a1/32.png) [@btimofte](https://community.wolfram.com/u/btimofte)\
**Post date:** [August 15, 2020, 4:14pm UTC](https://community.wolfram.com/t/unit-step-response/16572/4 "2020-08-15T16:14:51Z")

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Mathematica is better than Matlab Symbolic toolbox for nicely formatted equations.