A range of each variable value over which the function is positive

Questions
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1

There is a function with 8 variables. There are certain constraints for each variable. The constraints are as follows. Under these constraints, I want to know when the function is positive and when it is negative. FunctionSign didn’t work for me. Also Reduce did not work.

a>0, b>0, c>0, d>0, e>0, f>0, 1>=g>=-1, 1>=h>=-1

How can I learn if there is a range of each variable value over which the function is positive or negative.

2

It depends on how complicated your function is. For example

function = a + b - c;
Reduce[function > 0 &&
  And[a > 0, b > 0, c > 0, d > 0, e > 0,
   f > 0, 1 >= g >= -1, 1 >= h >= -1]]
3

The function is very complicated. It does not work for me.

4

Please provide full details and code about your problem to make it easier for other members to help you.

5

Possibly this is not tractable for your example. But it won’t work for anyone if the code is not made available.