Getting a 35S/33S to behave - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: General Forum (/forum-4.html) +--- Thread: Getting a 35S/33S to behave (/thread-1161.html) Getting a 35S/33S to behave - Matt Agajanian - 04-24-2014 06:02 PM Hello all. Let me cite the trig issue of the 33s/35s. Although trig operations near 90 degrees are a dud, is there a means to normalise a near 90 value so that a trig function can return an accurate result? Would converting the angle from degrees to radians/grads and calculating the trig function in radians/grads help? RE: Getting a 35S/33S to behave - r. pienne - 04-24-2014 06:08 PM Try it and see. RE: Getting a 35S/33S to behave - Matt Agajanian - 04-24-2014 06:15 PM Okie doke. RE: Getting a 35S/33S to behave - Thomas Klemm - 04-24-2014 07:30 PM (04-24-2014 06:02 PM)Matt Agajanian Wrote:  Although trig operations near 90 degrees are a dud, is there a means to normalise a near 90 value so that a trig function can return an accurate result? Use $$\sin(x)=\cos(90-x)$$ and $$\tan(x)=\frac{1}{\tan(90-x)}$$. Quote:Would converting the angle from degrees to radians/grads and calculating the trig function in radians/grads help? Probably not. Replace $$90$$ by $$\frac{\pi}{2}$$ in the formulas above when using radians mode. Cheers Thomas RE: Getting a 35S/33S to behave - Matt Agajanian - 04-24-2014 07:32 PM (04-24-2014 07:30 PM)Thomas Klemm Wrote:   (04-24-2014 06:02 PM)Matt Agajanian Wrote:  Although trig operations near 90 degrees are a dud, is there a means to normalise a near 90 value so that a trig function can return an accurate result? Use $$\sin(x)=\cos(90-x)$$ and $$\tan(x)=\frac{1}{\tan(90-x)}$$. Quote:Would converting the angle from degrees to radians/grads and calculating the trig function in radians/grads help? Probably not. Replace $$90$$ by $$\frac{\pi}{2}$$ in the formulas above when using radians mode. Cheers Thomas Thanks! Those are normalisation techniques I can live with. RE: Getting a 35S/33S to behave - Matt Agajanian - 04-24-2014 10:05 PM Okay here's a test: sin(1.566981956radians) and cos(0.003814371radians) yield 0.999992725295 on the 35S sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725295 on the 11C sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725303 on the 32S-II sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725303 on the 42S So, what's the verdict? RE: Getting a 35S/33S to behave - Thomas Klemm - 04-25-2014 12:54 AM (04-24-2014 10:05 PM)Matt Agajanian Wrote:  Okay here's a test: sin(1.566981956radians) and cos(0.003814371radians) yield 0.999992725295 on the 35S sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725295 on the 11C As the HP-11C can only handle 10 digits I assume there's a typo. I get sin(1.566981956) = 0.9999927253. I might not get why you use different input for the 35S and the other models. Quote: sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725303 on the 32S-II sin(1.5669819576radians) and cos(0.00381437113radians) yields 0.999992725303 on the 42S So, what's the verdict? It appears there's a problem with small values as well. From a previous thread about the HP-33S: Quote:105 * sin(0.0001) HP-32SII 9.99999998333 HP-33S 9.99999998300 actual 9.99999998333 You could try another identity: $$\sin(x)=2\sin(\frac{x}{2})\cos(\frac{x}{2})$$. Code: 2 / 1 ->R * 2 * Don't search too long for ->R on the HP-35S. Cheers Thomas