Error in solving equation

Forum|Forum|11 years ago
January 22, 2015
3 replies
4150 views

Hello everyone

I need to find the value of a variable (Dev) per iteration, assigning an initial value, but I get error and truth do not know why.

Hope you can help

Other

Best answer by Werner_E

You could do as I already wrote and solve for all three unknowns, but I thought it would be a better idea to turn Re and v.1 into functions of D.ev which they obviously are.

Now there are only three inequalities for D.ev left and not a single equations. So you have a range of valid values for D.ev and Find will give you the smallest one (3.069 in). If you chose different(higher) guess values you get different results.

In your second solve block there is a unit mismatch.

W

Werner_E

25-Diamond I

Attach your file, not just a picture.

It looks to me that v.1 and Re are unknown, too, and so you will have to search for all three unknowns and provide guesses for all of them. But you only have two equations!??

B

BPP

Author

1-Visitor

Sorry, This is the file

1_Equation-solve-xmcd.zip

W

Werner_E

Answer

25-Diamond I

You could do as I already wrote and solve for all three unknowns, but I thought it would be a better idea to turn Re and v.1 into functions of D.ev which they obviously are.

Now there are only three inequalities for D.ev left and not a single equations. So you have a range of valid values for D.ev and Find will give you the smallest one (3.069 in). If you chose different(higher) guess values you get different results.

In your second solve block there is a unit mismatch.

1_WE150122_Equation-solve-xmcdz.zip

B

BPP

Author

1-Visitor

Thanks Werner. One last question, as I can do to calculate "Dev" for each value in the case of multiple input values.

Thanks in advance

W

Werner_E

25-Diamond I

It may work if you vectorize ALL calculations dealing with those vectors.

The other (and in my opinion better) way is to make v1, Re functions of Q, p1, etc and turn the solve block into a function of all those variables you like to change. Then call that function with your vectors as arguments.