Convert vector element into a scaler for evaluation in a while loop

[ThermoStan]

Hi all,

I am attempting to extract a vector element piecewise within a while loop and assign it to the while evaluation variable for test.  I am able t do this once before I enter the loop but I cannot do this once in the loop and I get the "Array index is invalid message".  Is there a way to conveniently extract the element and assign it to the evaluation variable?  I am not a strong coder, clearly, I do not understand something.

Any help would be greatly appreciated.

[terryhendicott]

Hi, zero based array indexing is the default.  With one unknown only have columns 0 and 1

[Fred_Kohlhepp]

You have an undefined variable " n ".  You test for n>0, which fails so the Rkadapt never executes.

[Werner_E]

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@Fred_Kohlhepp wrote:

You have an undefined variable " n ". 

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n is delivered as the first function argument.