error in home not in CAS, confused

[resolved]

for the follow problem:

-40*LN[(128-160)/160]

I get an “Error:Invalid input” when calculated in Home Mode
whereas in CAS I get “-40*LN(-1/5)” whose approx value is 64.3775

why does the equation work in CAS Mode, but NOT in Home Mode????

[Thomas Ritschel]

By taking the logarithm of a negative argument you will get a complex result (which means that your approx. CAS result is also wrong).

For example: ln(-1/5) = -1.60943791 + 3.14159265*i

To get this on your HP Prime you'll need to enable the option "Allow complex output from real input" in the settings menu.

[Tim Wessman]

(07-31-2014 12:19 PM)Thomas Ritschel Wrote:  (which means that your approx. CAS result is also wrong).

Indeed. It was fixed in the last update. I recommend you update.

[resolved]

(07-31-2014 01:43 PM)Tim Wessman Wrote:  

(07-31-2014 12:19 PM)Thomas Ritschel Wrote:  (which means that your approx. CAS result is also wrong).

Indeed. It was fixed in the last update. I recommend you update.

I did update some time ago, unless a new update snuck by me

my CFO output is:
EA656 Version Info
DATA Version: V0.032.6030
OS Version: V0.032.6030
Released Version: V1.04
PCB Version: 00
Touch IC FW Ver: 26

is this the current version????

I can't tell you where my head was at when I wrote this thread, but the equation still does not work in Home Mode and the approx output in CAS Mode is:

64.3775164974-125.663706144*i

[Joe Horn]

(08-03-2014 02:05 AM)resolved Wrote:  

(07-31-2014 01:43 PM)Tim Wessman Wrote:  Indeed. It was fixed in the last update. I recommend you update.

I did update some time ago, unless a new update snuck by me

my CFO output is:
EA656 Version Info
DATA Version: V0.032.6030
OS Version: V0.032.6030
Released Version: V1.04
PCB Version: 00
Touch IC FW Ver: 26

is this the current version????

Yes it is. Easier way to see current version: Home, Help, Tree, up-cursor, Enter.

(08-03-2014 02:05 AM)resolved Wrote:  I can't tell you where my head was at when I wrote this thread, but the equation still does not work in Home Mode and the approx output in CAS Mode is:

64.3775164974-125.663706144*i

As Thomas Ritschel mentioned above, it WILL work in Home if you turn on complex mode. Press Shift Home, left-cursor twice, +, Home. Voila!

[resolved]

Thanks Joe for the easy to follow instructions, that will as least eliminate one more confusing message.

when calculating the natural log of a negative number in Home Mode, instead of just receiving a meaningless message “Error: Invalid Input” which leaves the user frustrated as to what they did wrong, couldn't HP just program in “no real values for negative logs, use CAS Mode for complex values.” Or "turn on complex mode in Home settings." We are humans that tend to forget and a helpful reminder would make the HP Prime more “user friendly”

just seems that some programmers are passive aggressive and want to set the user up for failure or they think they are creating a computer game instead of the useful tool and want to hide information from the user. .

Another example: when going into the EA656 Diagnostic Mode, item 9. says “RESET” In the simple minds of non-programmers, RESET evokes images of memory erasures, loss data, the END OF THE WORLD and should not be tread upon. In this case, reset means exit the diagnostic program, so why not just use simple plain English and say “EXIT.” It would make the calculator more “user friendly” for simple minded folk like myself.

[Watanabe]

I agree with all yours points, in special with : how exit the diagnostics mode... I was searching the answer and found your topic. I though the ERASE option was for clear the memory....

Thanks!