## 110 Reputation

18 years, 84 days
I have developed a Physiologically Based Pharmacokinetic program (PKQuest) in Maple. Application of this program to more than 30 different drugs has been described in a series of publications. The program and the publications are freely available at www.pkquest.com.

## dsolve for system of 3 real eqs returns ...

Maple

I want to solve a system of 3 simple real linear odinary differential equations.

The solution using dsolve has some extra imaginary terms with very small (10^-10) coefficients.   How to I get just the real part of the solution.

Here is an example code:

v1 := 1;
v2 := 0.5;
k := 0.12;
p1 := 0.328;
p2 := 0.74;
l1 := 0.31;
l2 := 1.16;
sysode := diff(Cp(t), t) = -(p1 + p2 + k)*Cp(t) + l1*C1(t) + l2*C2(t), diff(C1(t), t) = (p1*Cp(t) - l1*C1(t))/v1, diff(C2(t), t) = (p2*Cp(t) - l2*C2(t))/v2;
ics := Cp(0) = 0.347, C1(0) = 0., C2(0) = 0.;
sol := convert(dsolve([sysode, ics]), float);

## Error attempting to install Physics Pack...

Maple 2021

When I click on the "install" option for the update to the Physics Package, get the following error message:

Fetching package "Physics Updates" from MapleCloud...
ID: 5137472255164416
Version: 988
URL: https://maple.cloud

An error occurred, the package was not installed:

## Maple Physics: How to create contravari...

Maple 2020

I would like to use the command "TensorArray"  to create the contravariant tensor.  As seen in the following simple routine, the command output seems to assign values to the contravariant tensor, but, on the last line, the contravariant value is still unassigned.

## Cannot update the Maple Physics Package...

Maple 2020

I  installed Maple 2020 a week ago.   When I try to update the Maple Physics Package, the installation stalls.

Output to the command  Physics:-Version(latest):

`The "Physics Updates" version "872" is installed but is not active. The active version of Physics is within the library C:\\Program Files\\Maple 2020\\lib\\maple.mla, created 2020, March 4, 19:36 hours`

I note that there was similar complaint in June.  I am surprised that this has not yet been fixed. The reply in June seemed to be do a manual update, but I am unclear how to do that.   I can download the latest package, but I do not know how to  (or where) to install this package.  Do I just delete the version in C:\\Program Files\\Maple 2020\\lib\\maple.mla and paste the new version?

I would greatly appreciate any help since the main reason I purchased the new Maple 2020 was to use the most recent versions of the Physics package.

## Maple Physics -Tensors: how to derive ...

Maple 2020

I think the Maple Physics package has the promise to revolutionize the teaching of physics. Two recent tutorials have been very helpful (“Vectors in Spherical coordinates using tensor notation” and “A Complete Guide for performing Tensors computations using Physics”).   Unfortunately, despite these, I still have problems even when trying to use it for simple things. No doubt this is primarily a sign of my limitations. However, in the hope that others might share this, I have the following question.

As an exercise, I would like to use the Maple Physics Tensor notation to derive the expression for acceleration in spherical coordinates – identifying Coriolis force, etc.  I can’t get past the first step – how to define the tensor dx/dt.   That is, how do I write the time derivative of the Maple space coordinates [X].  I assume that this can be done in about 3 steps, if someone would be kind enough to humor my ignorance. Thanks in advance.

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