That is a beautiful picture of a beautiful calculator! I love mine, too, but it does fall down rather quickly in some of the trig and differentiation edge cases.
this post was submitted on 27 Sep 2025
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@JakeSparkleChicken Thanks! I like the UI so far, lots of features seem implemented well. Have heard about issues with trickier integration, but not about trig - do you have any examples?
Just to follow up, there's a great thread on integration on the W506T here: https://www.hpmuseum.org/forum/thread-13968.html. The upshot is that is that the 506 uses Simpson's, which will falls down in some use cases, especially ones with asymptotic curves, and needs the user to select more iterations manually.
In terms of trigs I tried these two: cos(1.57079632 rad) = 6.79491584e-9, which is correct to 4 decimal places. Not bad, better than older Casios, not as good as the latest Casio platforms which get at least 9 digits correct. arcsin(arccos(arctan(tan(cos(sin(9 deg)))))) = 9.0000001 which is reasonable.
Sorry about that! I spoke from memory instead of checking my data first. The Trig functions are pretty middle of the pack, it's the integration and the processor speed that are not that great. sum((e^sin(atan(x)))^(1/3), 1, 1000) takes six minutes to run, but at least it completes. The Casio fx-991CW takes just over on minute, and even the TI-36X Pro only takes four minutes.
Yes, I think the processor must be slower, and as a result, the integration is more limited. They also have different methods of differentiation, and maybe the Casio one is superior.
I don't have a 991-CW, but do you know what it can do with the complex functions? My experience of older Casio 991s is that complex is limited to arithmetic operations only. This seems to be the case on the W506T - i.e. it won't do Log or Sin of a complex number. But then many 'scientific/non-graphing' calculators (except for HP) don't.
As far as complex numbers go, the 991CW doesn't add anything that most other flagship scientific calculators can do.
@dm319 @calculators
The UI looks way better than the Casio I ended up getting! What model number is that? I can't quite make it out. Would be interesting to see if it's available here
@SmartmanApps @calculators It's a EL-W506T, though might have a different name in other markets.
@SmartmanApps @calculators In fact it might be called the EL-W516T where you are?
@dm319 @calculators
I think this is it, and cheaper than the Casio! 😡
https://www.officeworks.com.au/shop/officeworks/p/sharp-scientific-calculator-black-white-el-531th-shel31thw
@SmartmanApps @calculators No it's not that one (the one shown is a two-line type), although, as you know, all Sharps will evaluate the same way, even back to your original 531WH. I'll have a peek on that website...
@dm319 @calculators
Oh ok. Didn't notice that difference
I feel like you need this calculator...
Next to the fx-85GT which I think is similar to your 8200AU. They are certainly based on the same calculating platform. The Casio's latest (cw) platform is very high precision, I think 20+ digits, and the Sharp is 16, not that anyone needs more than 10 though. The display on the Casio is better - higher resolution and slightly better contrast, but the Sharp is still good and sufficient for needs. The Sharp is far more direct in use - the 'change' button just cycles through output types. It will convert straight to other bases or Deg/Rad/Grad, and change the mode at the same time. Memory handling seems to me to be WAY better (i.e. what way are you meant to store a result into variable 'A' on the Casio? - you think it should be the variable button, but then its a menu select for the variable, another menu select for what you want to do with it, and even then it isn't obvious how to store your result!). The Sharp is just STO A or STO B etc. Also 1÷2E3 gives the expected answer.
I will post you one from the UK if you can't get one there!