I'm lost with the cost function to be evaluated when carrying out a sensitivity analysis
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I'm trying to carry out a sensitivity analysis on my simulink model that represents the Penman-Monteith equation and estimates Evapotranspiration (ETo) values. Well, I want to find out how any of the parameters I need to estimate ETo influences ETo. Everything went well until I had to evaluate the cost function for any of the samples previously created. It is here wher I get stuck. What's actually a cost function, what does it do, and what would be the most appropiate cost function in my case? I can provide more information about my model, inputs or whatever. Thanks to those who answer me.
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monika dixit
2018-4-24
how did you model the Penman-Montieth equation in Simulink. Could you please guide?
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Star Strider
2016-8-17
A ‘cost function’ measures the variation from the actual performance of your model and the ideal performance. I don’t know what you’re doing, but one example of a cost function is a sum-squared-error function that in nonlinear regression measures the squared difference between the value of the function with a given set of parameter values and the data it is desired to approximate. The optimization of the function adjusts the parameter values to minimise the cost function.
A sensitivity function is the Jacobian of the cost function, the partial derivatives of the cost function with respect to each parameter. This allows you easily to see the effect — or ‘sensitivity’ — of each parameter on the behaviour of the function.
This is a simplified explanation to get you started. An Internet search or any book on optimisation or nonlinear regression will provide you with a much more detailed — and mathematically rigourous — discussion.
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