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+--- Thread: [SOLVED] Given (|) in programming? (/thread-6318.html)
[SOLVED] Given (|) in programming? - CH3791 - 05-29-2016 04:57 AM
Hi, I am trying to make a program that calculates x intercepts. Right now, it can calculate the answer, but I can't make it restrict the domain.
I understand you can do this directly in the CAS app:
solve(SIN(x)=0,x)|{(x>-10) AND (x<10)}
{-3*pi, -2*pi, -pi, 0, pi, 2*pi, 3*pi}
But when I put that kind of syntax into my program, it returns "Error: Invalid input".
Code:
EXPORT XINT(expression,domainlow,domainhigh)
BEGIN
LOCAL equation;
LOCAL variable;
LOCAL answer;
variable:="x";
equation:=EXPR(LOWER(STRING("0="+expression)));
answer:=CAS.solve(EVAL(equation),EVAL(variable))|{(EVAL(variable)>-10) AND (EVAL(variable)<10)};
print("X-INTERCEPT(S)");
print(answer);
RETURN "DONE";
END;Any ideas?
RE: Given (|) in programming? - roadrunner - 05-29-2016 08:24 AM
I'm not sure that syntax, using the "|" operator, is valid within a program; but using assume() and additionally() does appear to work. See modified program below:
Code:
EXPORT XINT1(expression,domainlow,domainhigh)
BEGIN
LOCAL equation;
LOCAL variable;
LOCAL answer;
variable:="x>"+string(domainlow);
CAS.assume(EVAL(variable));
variable:="x<"+string(domainhigh);
CAS.additionally(EVAL(variable));
// variable:="x";
equation:=EXPR(LOWER(STRING("0="+expression)));//EXPR means convert to a string.
answer:=CAS.solve(EVAL(equation),"x");
print("X-INTERCEPT(S)");
print(answer);
RETURN "DONE";
END;RE: Given (|) in programming? - CH3791 - 05-29-2016 08:47 AM
Thanks roadrunner, your code works perfectly. One thing I would add though is:
purge(x);
at the very end just before RETURN "done", so that the domain gets deleted and won't affect future calculations involving x.