What is wrong with this division?

**mackrackit** · - 5th March 2010, 04:07

Looks like you need Extra_LONGS for that.

The multiplication over flows the LONG VAR.

Try

Code:

current_voltage = 49800
P = 7861 * current_voltage	
P = P / 4868 * 10

**ScaleRobotics** · - 5th March 2010, 06:25

Nevermind.

**tenaja** · - 5th March 2010, 16:03

Originally Posted by mackrackit

Looks like you need Extra_LONGS for that.

The multiplication over flows the LONG VAR.

Try

Code:

current_voltage = 49800
P = 7861 * current_voltage	
P = P / 4868 * 10

Dave, I thought Longs were 4 bytes... ?
49800 x 7861 = 391477800 = $1755 7A28 ...which is 4 bytes...

**Acetronics2** · - 5th March 2010, 16:22

Hi, tenaja ...

I think you've been cheating ...

Dave is the best ...

LONGS are SIGNED ... ( Manual p.24 )

Alain

**tenaja** · - 5th March 2010, 16:31

Yeah, but it's still only 29 bytes. Does the "sign" take up 4 bytes?

**mackrackit** · - 5th March 2010, 16:47

The OP had
49800 * 78610 = 3914778000

**tenaja** · - 5th March 2010, 17:29

Yes, but he also said it did not match the calculator output. My point was that the calculator proved it fits within the constraints of a Long.

**mackrackit** · - 5th March 2010, 17:31

A calculator gives
3914778000
LONGS can be
2147483647

**Acetronics2** · - 5th March 2010, 17:39

Originally Posted by tenaja

Yeah, but it's still only 29 bytes. Does the "sign" take up 4 bytes?

in fact, the sign is bit 31 ...

so, ... better let's say +/- 3 3/4 bytes ... for maximum value

Alain

Thread: What is wrong with this division?