Possible to have incorrect numbers with PW_REL?

[jychoi-hpc]

I am trying to check if I am getting right values with PW_REL method.
Wi the following line in "sz.config" (other parts are same with the file in example):

errorBoundMode = PW_REL
relBoundRatio = 1E-2

After running the following line followed by decompression, the pw relative error I calculated is different from what I expected (I expect lower than 1E-1):

$ ./testdouble_compress sz.config testdouble_8_8_128.dat 8 128  

My calculation is 0.159883. I used some code something like:

    for (i = 0; i < nbEle; i++)
    {
        rel = fabs(ori_data[i]-data[i])/fabs(ori_data[i]);
        if (relMax < rel) relMax = rel;
    }
    printf ("Max pw_relative error = %g\n", relMax);

I am wondering if this is the right result or I did use incorrectly.

[disheng222]

As you know, there are two types of relative errors defined in SZ. REL means the value_range based relative error. That is, absErrBound = relBoundRatio * (max-min) for each data point. PW_REL means the point-wise relative error bound. Please note that relBoundRatio is used only for value_range based relative error mode. For PW_REL, please set pw_relBoundRatio = 1E-4 and set segment_size = 25. If you want to get strict bound effect for each data point, you need to use pwr_type = MIN. Best, Sheng 2017-09-07 16:59 GMT-05:00 Jong Choi <notifications@github.com>:

…

I am trying to check if I am getting right values with PW_REL method. Wi the following line in "sz.config" (other parts are same with the file in example): errorBoundMode = PW_REL relBoundRatio = 1E-2 After running the following line followed by decompression, the pw relative error I calculated is different from what I expected (I expect lower than 1E-1): $ ./testdouble_compress sz.config testdouble_8_8_128.dat 8 128 My calculation is 0.159883. I used some code something like: for (i = 0; i < nbEle; i++) { rel = fabs(ori_data[i]-data[i])/fabs(ori_data[i]); if (relMax < rel) relMax = rel; } printf ("Max pw_relative error = %g\n", relMax); I am wondering if this is the right result or I did use incorrectly. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#16>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AJW1Sece9QCMnmCDMC_33p6xkaKXm84wks5sgGdPgaJpZM4PQcfv> .

[jychoi-hpc]

I see. After using the above parameters, it works now. Thanks.

[jychoi-hpc]

I got another problem related with this. If I use SZ_Init_Params instead of SZ_Init(file), I have no compression with PW_REL. It works with REL or ABS.

I used the following code for init:

    sz_params sz;
    memset(&sz, 0, sizeof(sz_params));
    sz.max_quant_intervals = 65536;
    sz.quantization_intervals = 0;
    sz.dataEndianType = LITTLE_ENDIAN_DATA;
    sz.sysEndianType = LITTLE_ENDIAN_DATA;
    sz.sol_ID = SZ;
    sz.layers = 1;
    sz.sampleDistance = 100;
    sz.predThreshold = 0.99;
    sz.offset = 0;
    sz.szMode = SZ_BEST_COMPRESSION; //SZ_BEST_SPEED; //SZ_DEFAULT_COMPRESSION;
    sz.gzipMode = 1;
    sz.errorBoundMode = PW_REL; //REL; //PW_REL;
    sz.absErrBound = 1E-4;
    sz.relBoundRatio = 1E-3;
    sz.psnr = 80.0;
    sz.pw_relBoundRatio = 1E-2;
    sz.segment_size = 32;
    sz.pwr_type = SZ_PWR_MIN_TYPE;
    SZ_Init_Params(&sz);

[disheng222]

Oops...The settings were not successfully set by SZ_Init_Params(&sz). Bug is fixed. Thanks. 2017-09-08 20:26 GMT-05:00 Jong Choi <notifications@github.com>:

…

I got another problem related with this. If I use SZ_Init_Params instead of SZ_Init(file), I have no compression with PW_REL. It works with REL or ABS. I used the following code for init: sz_params sz; memset(&sz, 0, sizeof(sz_params)); sz.max_quant_intervals = 65536; sz.quantization_intervals = 0; sz.dataEndianType = LITTLE_ENDIAN_DATA; sz.sysEndianType = LITTLE_ENDIAN_DATA; sz.sol_ID = SZ; sz.layers = 1; sz.sampleDistance = 100; sz.predThreshold = 0.99; sz.offset = 0; sz.szMode = SZ_BEST_COMPRESSION; //SZ_BEST_SPEED; //SZ_DEFAULT_COMPRESSION; sz.gzipMode = 1; sz.errorBoundMode = PW_REL; //REL; //PW_REL; sz.absErrBound = 1E-4; sz.relBoundRatio = 1E-3; sz.psnr = 80.0; sz.pw_relBoundRatio = 1E-2; sz.segment_size = 32; sz.pwr_type = SZ_PWR_MIN_TYPE; SZ_Init_Params(&sz); — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#16 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AJW1SY9ueynY4mHDQFvz4nGhnKcNVooAks5sgelNgaJpZM4PQcfv> .