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# these values can not be compared

## these values can not be compared

(OP)
Hi, first, I would like to say i am very new for Mathcad. My questions might be very easy for someone.

You can see an error in my file,  the attachment.
I've tried to calculate drag force at each water depth.I can calculate current at each water depth. But when i tried to use the results(current) in another question to find force, I got "these values can not be compared".

I know that there is something about array or others but i don't know how to fix it.

<After i calculate the force, i still need to use the force in further equations. this would be the same problem how to identify array for the eq.>

another question, how i can adjust space between each row(equation boxes)?

Thank you so much.

### RE: these values can not be compared

I could not open your file with MathCad 14.  Are you using lb or lbf for force?

### RE: these values can not be compared

Mathcad's range variables can be quite annoying, at times.  A range variable, like d, is not a vector, and so some operations that work in some expressions will not work in others.  You can also do your current calculation as a single if.

do the following:

i:0;3000    d[i:-i

current(d):if(-40<=d<=0,(-0.5*(-d)/400)+0.7,0.2)

drag[i:-1/2*cd_wcp*area_wcp*rho*current(d[i)

where
: is the keystroke for the := assignment
[ invokes the array subscript operator

### RE: these values can not be compared

(OP)
Thank you for both. I can do it.

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