## 5 Reputation

1 years, 170 days

## Error in Matrix - cannot determine if tr...

Maple 2019

Hello! I have a Maple sheet that is functional in some versions of Maple but not others. It works perfectly in Maple 18 (which is the version with which it was written), but when running it in Maple 2019, I see the following error:

• "Error, (in Matrix) cannot determine if this expression is true or false: Distance(Vector[row](3, {(1) = 0., (2) = 1.313799622, (3) = 0}), Vector[row](3, {(1) = 0., (2) = -1.313799622, (3) = 0})) < 99999999999999999999/100000000000000000000"

And believe that it is related to the following lines of code:

• R := Matrix(N, (i, j) -> Distance(coords[i], coords[j]) ;
• S := Matrix(N, (i, j) -> if i = j then 1 elif R[i, j] < 3 then (1+C*R[i, j]+(2/5)*C^2*R[i, j]^2+(1/15)*C^3*R[i, j]^3)*exp(-C*R[i, j]) else 0 end if)

It seems as if it cannot compute a distance between two points (as given in the form of two vectors). I have imported the Student:-Precalculus package, along with ArrayTools and LinearAlgebra, at the start of the sheet, but am wondering if there is an issue with this package in other versions of Maple. The full sheet can be provided if more information is needed, but I'm pretty sure that portion is the problem. Any help would be greatly appreciated.

Sheet: testsheet.mw

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