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More PDEsolve help!

ptc-5700236
1-Newbie

More PDEsolve help!

My previous question was solved, but now I'm having another issue with the same mathcade file. The first 8 equations in the solve block are correct, so the error lies within my Temperature equation, I believe. The error I'm getting right now states 'the number of functions must be equal to the number of equations.'

1 ACCEPTED SOLUTION

Accepted Solutions

You had two mistakes in the expression for Temp.t: a missing bracket at the end, and an incorrect expression involving the H2O term in the top line. These are fixed in the attached.

However, I have to say that you have chosen a ridiculous way to construct Temp.t! It's no wonder there were some mistakes. Break this sort of expression into smaller, bite-size chunks, using more function definitions before the solve block, so that it is easier to see what is happening and easier to debug.

Alan

Found a third error (in the denominator of Temp.t). Corrected file attached.

Version c is a simplified (though still pretty complicated!) version that is equivalent to version b, but is easier to debug (I think).

However, I think there must be something wrong with your basic equations for dTemp/dt, as it produces some silly temperatures.

Sometimes when I run either of these worksheets I get a "repeated singularity" error, but simply re-calculating the worksheet usually gets rid of it!!!

View solution in original post

1 REPLY 1

You had two mistakes in the expression for Temp.t: a missing bracket at the end, and an incorrect expression involving the H2O term in the top line. These are fixed in the attached.

However, I have to say that you have chosen a ridiculous way to construct Temp.t! It's no wonder there were some mistakes. Break this sort of expression into smaller, bite-size chunks, using more function definitions before the solve block, so that it is easier to see what is happening and easier to debug.

Alan

Found a third error (in the denominator of Temp.t). Corrected file attached.

Version c is a simplified (though still pretty complicated!) version that is equivalent to version b, but is easier to debug (I think).

However, I think there must be something wrong with your basic equations for dTemp/dt, as it produces some silly temperatures.

Sometimes when I run either of these worksheets I get a "repeated singularity" error, but simply re-calculating the worksheet usually gets rid of it!!!

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