Now consider 0 * infinity = Q for any non-zero Q in the set of complex numbers (including reals). There is no such answer that I can give you to satisfactorily explain this. @Jamal Ahmad. now take three different expressions that are basically 0*inf: You can get any value that you want, so Matlab goes with the IEEE 754 standard and says NaN. A deliberately coded inf or an inf produced as a result of an unbounded operation such as log(0) should indeed have the property that 0*inf is indeterminate. But if infinity = 0/0 and 0/0 is analytically 1, then infinity =? In other transfinite systems each infinite value has a unique nonzero reciprical (an infinitessimal). Not 0 in general, but logical(0) specifically. Depending on where the "zero" came from, there are different possible results we might then expect for any operation. since x->inf can be anything is could be larger than 0.00... so this still applies. My problem is that; one of the parts in the equation will result to infinity, and another part will result to zero. It’s merely a symbol used to describe the concept/characteristic of “infinity/infinite” (typically seen as a trend of some variable/function) in analysis. Then the product of them should give me zero BUT it gave me NAN. Suppose that I have a function f defined as a function g truncated over a compact set A. What does Infinity Divided by Infinity Equal? Like factorial(171) or exp(710) is all operations on finite numbers but the result is just too big to fit. Unable to complete the action because of changes made to the page. but Matlab give me NAN. Many Thanks, Yes, it is possible to make MATLAB not consider exp(1000) to be infinity. so if that holds then it must also hold that 0 * infinity = Q for all non-zero Q. If you remember how this was introduced in the mathematical analysis course you most likely took for many years ago you would see that the correct way to work with infinities is to work with limits for example. Mathematically, the value f(x) should be zero for every x outside A, no matter how g is defined. But is that true? Opportunities for recent engineering grads. What alternative value in the range, +/- 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368, good. this is because when you have infinity in Matlab you can't do anything with it. Choose a web site to get translated content where available and see local events and offers. But I agree with James Tursa that Matlab cannot determine whether f is defined only on a sub-domain and whether x0 is in the closure of this sub-domain. The point is, once you go down this road you end up in a spiral, one that cannot easily be resolved. Is it 0 or infinity or anything other? I tend to find thinking of it easier in this way: Infinity * 0, therefore, can be equal to anything. Anyway, a "truncation operator" to be used within anonymous functions would be very much useful. Be serious. After all, any number subtracted by itself is equal to zero, however infinity is not a real (rational) number. It is true that the result of 0*Inf is indeterminate when the latter is interpreted as the product between two limits - it simply doesn't make any sense if it is interpreted as a standalone expression. Other MathWorks country sites are not optimized for visits from your location. Of course, we need to find the cash … Even if infinity is really big, if there are zero amounts of infinity, that would make zero. I've checked three different math sites. The obvious solution to that problem is to say that the limit can not be set, or the limit does not exist. just thought of something! But the truth is, we don't know. That is why it gives you a NaN. Clearly though it cannot be all of them simultaneously. Well, divide through by Q to get, and 0/Q is 0 for all non-zero Q, so we have reached back to. You see that x cancels out and the answer is a/b. what is the value of zero*infinity ? A Line goes in both directions without end.. thanks for the answers. Why isn't zero multiplied by infinity equal to zero? You can change your choices at any time by visiting Your Privacy Controls. you know that zero * exp(800) should give me zero. but you then proceed to talk about 0*f(x) with respect to limits, rather than "as a standalone expression", whatever that means. As the sequence of values of x become very small numbers, then the sequence of values of y, the reciprocals, become very large numbers.The values of y will become and remain greater, for example, than 10 100000000. y becomes infinite. The product of 0 and infinity, mathematically, is not zero. The second meaning in MATLAB (and IEEE 754 arithmetic) is that floating point infinity is also used to stand in for "overflow produced by operations on finite numbers". The same applies for. It is often denoted by the infinity symbol ∞.. NO. if 0 * infinity = 1 is provable, then 0 * infinity = Q is provable for non-zero Q, which would make the product of 0 and infinity indeterminate because it could be any non-zero value.