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# Using the DES Y1 Likelihood

The Dark Energy Survey Y1 likelihood for the shear, clustering, and cross two-point measurements are available in CosmoSIS.

Here are the steps to using it.

## 1. Install CosmoSIS

Follow the instructions at the top of the main CosmoSIS wiki page.

## 3. Test-run the likelihood

Then you can run an example of the DES-SV cosmic shear likelihood by doing:

cosmosis examples/des-y1/params.ini

## 4. Explore further

This will just run a test, calculating the likelihood at a single point in parameter space. To explore the likelihood you can change to a real sampler - details are in `examples/des-y1/params.ini`

, as are details on what is happening in the likelihood and how to modify and experiment with it. You can also see `examples/des-y1/values.ini`

for the input parameters, and `examples/des-y1/priors.ini`

for the priors.

If you are new to CosmoSIS please see our front page for tutorials and reference information.

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