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Hello, I`m having trouble solving equations simultaneously in Matlab. I have three equations and three unknowns. Two equations are algebraic and one is a differential equation. Here are my three equations, any help would be appreciated: 
Subject: Solving 3 equations in Matlab From: Walter Roberson Date: 29 Nov, 2010 20:22:04 Message: 2 of 8 
On 101129 01:21 PM, amadd wrote: 
Thank you very much for your help. The equations are as they are. Ttank is a function of time. Toutw is dependant on Ttank and is considered a constant.I have tried running this model using Maple but it didn`t work. I`ll explain that this is a model for a solar collector that transfer heat to water in a tank. Ttank is the temperature of the fluid in the tank, this transfer heat to water in a pipe. I am to model the temperature increase of water over time. My equations are 100% correct, but you are right, I should replace 3.14 with pi. But, the main problem is that I do not know how to model them in matlab. Can you provide me with an answer now or do you need more help or information. I appreciate your reply. 
By the way Toutw is not be modelled differentially over time. But it is dependant on the Ttank (temperature of the tank) for increase as you can see from the 2nd equation which is: 
Subject: Solving 3 equations in Matlab From: Walter Roberson Date: 29 Nov, 2010 21:36:06 Message: 5 of 8 
On 101129 02:54 PM, amadd wrote: 
Subject: Solving 3 equations in Matlab From: Roger Stafford Date: 29 Nov, 2010 23:49:05 Message: 6 of 8 
amadd <amardi88@gmail.com> wrote in message <1735798820.23823.1291058514512.JavaMail.root@gallium.mathforum.org>... 
Hi, I will explain the system to you in further details: 
By the way regarding your question about logarithms, the log mean temperature difference is used to show the temperature change between the tank and the water pipe. It is present in the differential equation and the water pipe equation(3). It simply that (TtankTwaterin(20C)(TtankTwaterout(toutw)/ln(TtankTwaterin(20C)/(TtankTwaterout(toutw). Toutw is the temperature of the water outlet, Twaterin is the temperature of the water inlet which is constant at 20 and Ttank is the varying temperature of the tank with time. Anymore details I can provide? 
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