Re: Binary floating point format
Re: Binary floating point format
- Subject: Re: Binary floating point format
- From: Carl Hoefs <email@hidden>
- Date: Thu, 30 Mar 2017 19:09:40 -0700
> On Mar 30, 2017, at 6:40 PM, Steve Bird <email@hidden> wrote:
>
>
>> On Mar 30, 2017, at 8:25 PM, Carl Hoefs <email@hidden> wrote:
>>
>> I have megabytes of raw legacy science datasets that I'm trying to read into my app and ingest into an array of doubles. The data is supposed to be organized as a stream of 8-byte doubles. I do not know how these datasets were generated, so I don't know what format (big/little endian, byte swapped, etc) they are in.
>> Here is a hex dump of 4 binary doubles:
>>
>> 49BF7DE372533C05 A8C02FE3135B4F09 86C22FE37E630B05 27C2C4E3E258BA08
>
> A few minutes of LabVIEW work shows some semi-reasonable values if you swap bytes:
> BF49E37D5372053C = -0.000790058
> C0A8E32F5B13094F = -3185.59
>
> Do you know that those values are wrong?
Hmm, the -3185.59 doesn't look right. The data is _supposed_ to be:
1st double: Time value, monotonically increasing, usually starting near 0.00000
2nd double: Sensor value, oscillating waveform, centered about some arbitrary value
So I'm expecting data like:
0.011 0.57525634765625
0.012 0.45166015625000
0.013 0.29907226562500
0.014 0.13275146484375
0.015 -0.03173828125000
0.016 -0.18218994140625
0.017 -0.29602050781250
0.018 -0.38055419921875
...etc.
or even:
0.018 2089.66467285156250
0.020 2087.57525634765625
0.022 2085.45166015625000
0.024 2083.29907226562500
0.026 2082.13275146484375
0.028 2081.03173828125000
0.030 2080.18218994140625
0.032 2080.29602050781250
0.034 2079.38055419921875
0.036 2079.43060302734375
0.038 2078.44738769531250
0.040 2076.43640136718750
...etc
When I manually swap the bytes in my program, I still end up with invalid values.
-Carl
26 C3 E9 E2 6C 6A 38 0C 46 C3 E9 E2 6C 6A 40 0B 46 C3 E9 E2 83 6A DC 0A 66 C3 E9 E2 83 6A 0E 0B
A5 C3 EF E2 AF 6A 40 0B A5 C3 EF E2 C6 6A 40 0B C5 C3 F5 E2 C6 6A 16 0A C5 C3 F5 E2 DC 6A 0E 0B
26 C3 3C E3 9E 62 B2 09 26 C3 3C E3 9E 62 B2 09 26 C3 36 E3 B4 62 BA 08 06 C3 36 E3 CB 62 C2 07
45 C4 76 E3 44 6C 38 0C 25 C4 76 E3 5A 6C 06 0C 25 C4 76 E3 5A 6C DC 0A 05 C4 7D E3 70 6C DC 0A
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