Timeline for Error in storing the output of a module (subroutine) into an array
Current License: CC BY-SA 3.0
6 events
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| Jul 28, 2017 at 18:40 | comment | added | leastaction | Hi. Please close the question if forum rules so demand, as I am traveling now and won't be able to update it for another 24 hours. It seems there is no technical problem and these errors are warnings that arise because Coefficient is picking the coefficient of $dx^i \wedge dx^j$ in an expression and when $i=j$ this term is zero so the coefficient is undefined. The wedge indicates an exterior product. | |
| Jul 28, 2017 at 18:38 | comment | added | MarcoB | @leastaction As you can see, without the details of expression1 and expression2 to test with, the cause of your problem is unclear. Time to include the details of your code, or the question might be closed as missing valid code to reproduce. | |
| Jul 28, 2017 at 7:31 | comment | added | aardvark2012 |
The ::ivar error is often generated when a variable has inadvertently been given a value (search for "ivar" on this site). That is, somewhere your code is trying use 0 as a variable. Your error message Coefficient::ivar indicates that this is occurring in Coefficient. I would guess the problem is with your expression2, leading to something along the lines of Coefficient[(x + y)^2, 0] (for certain entries in your array), which generates the exact same error message as you're getting.
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| Jul 28, 2017 at 5:02 | comment | added | leastaction | Hi @aardvark2012, thanks for your reply. On the contrary, the Module works fine -- all calls to it are non-erroneous. It is only when I am dumping its output into an array do I generate errors. So it is the opposite of what you say. Does that help pinpoint the problem? | |
| Jul 28, 2017 at 3:08 | comment | added | aardvark2012 |
It looks like the error is from the Coefficient in your definition of Riemann, not from the creation of your array which, as you say, seems to work fine. Something odd might be going on with your definition of Riemann, which you could clean up as Riemann[mu_, nu_, rho_, sigma_] := Module[ *etc* ].
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| Jul 27, 2017 at 23:20 | history | asked | leastaction | CC BY-SA 3.0 |