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+--- Thread: POLYROOT does not always work inside a program [SOLVED] (/thread-5466.html)
POLYROOT does not always work inside a program [SOLVED] - JMB - 01-06-2016 08:45 PM
I have found a strange behavior (a bug?) while using the function POLYROOT inside a program. My firmware version is 2015 6 17 (8151).
The calculator's built-in help states that the argument of this function can be either a symbolic expression or a vector of coefficients, but I have found that a list of coefficients also works as the function's argument. So both POLYROOT([1 -3 2]) and POLYROOT({1, -3, 2}) return the same answer: {1, 2}, in Home and in CAS.
The problem arises when I use this function inside a program, for example:
EXPORT Test()
BEGIN
POLYROOT([1, -3, 2]);
END;
The first thing worth noting in that commas are needed inside [ ], otherwise you get a syntax error when you tap the Check button. Then when you run the program you get the following error message:
Test
"POLYROOT(ListToMat(EVAL
LIST({0,1,3,1-3,2})))
Error: Bad Argument
Value)"
After trying different numeric values, I have found that this error only happens inside a program, when using [ ] and at least one value is negative. So we have, for example:
POLYROOT({1, 3, 2}): correct answer {-2, -1}
POLYROOT([1, 3, 2]): correct answer {-2, -1}
POLYROOT({1, -3, 2}): correct answer {1, 2}
POLYROOT([1, -3, 2]): error, as stated before
RE: POLYROOT does not always work inside a program - DrD - 01-06-2016 09:53 PM
That does seem to be a problem, and a possible work-around is to pre-assign the vector to a matrix variable:
Code:
EXPORT tmp()
BEGIN
M0:=[1,-3,2];
POLYROOT(M0);
END;Also, if passed as a string object, it seems to work:
Code:
EXPORT tmp()
BEGIN
POLYROOT("[1,-3,2]");
END;-Dale-
RE: POLYROOT does not always work inside a program - Tim Wessman - 01-11-2016 05:34 PM
Hello,
I'm fairly sure this one has been caught already, but I will add a specific bug for this case and get it into our testing. Thanks!
RE: POLYROOT does not always work inside a program - JMB - 04-30-2016 09:55 AM
Corrected in firmware 10077.
Thanks to the HP Prime Team!