IBM TechXchange Group

View Only
• 1.  RTRT - Rationale test real time

Posted 23 days ago
Edited by Lorraine Rizzuto 18 days ago

Hi Team,

I have a question related to the parameter from the below function

--------------------------------------------------------------------------------
static float ComputeFactor(float IAS, float Alt, float Temp)
{
float  dpp,
mach,
last,
p,
speed_of_sound,
TAS;

if (Alt< -1000.0f) {
Alt = -1000.0f;
}
if (Alt>65000.0f) {
Alt = 65000.0f;
}
if (IAS<20.0f) {
IAS = 20.0f;
}
if (IAS>650.0f) {
IAS = 650.0f;
}
if (Temp<-100.0f) {
Temp = -100.0f;
}
if (Temp>100.0f) {
Temp = 100.0f;
}

if(Alt > ALT_TR) {
p = P_TR_PSF * expf(-4.806346E-5f * (Alt - ALT_TR));
}
else {
p = P_0_PSF * powf(1 - 6.8755856E-6f * Alt, P_LAPSE);
}

dpp  = (P_0_PSF * (powf(1 + 0.2f * (IAS/CS_0)*(IAS/CS_0), 3.5f) - 1) / p) + 1;
mach = sqrtf(5 * (powf(dpp, 0.2857142857f) - 1));

if(mach > 1.0f) {
/* Iterate with Rayliegh's Formula to account for shock effects */
do {
last = mach;
mach = 0.881285f * sqrtf(dpp * powf(1 - 1/(7*mach*mach), 2.5f));
} while(fabsf(mach-last) > 0.005f);
}

speed_of_sound = 643.855f * sqrtf((Temp+273.15f)/273.15f);
TAS            = speed_of_sound * mach;

return(TAS/IAS);
}
--------------------------------------------------------------------------------

Issue:
When input Alt 'init = 65001' is driven then as per the functionality the output should be Alt 'ev = 65000'.
But test report is reflecting Alt 'ev = 65001'

Need suggestion on this behavior?

------------------------------
Venkata Krishna Murty Hari
------------------------------

• 2.  RE: RTRT - Rationale test real time

Posted 18 days ago

Hi Venkata,

Can you expose 3 digits after the decimal ''.'' to see if there are a fraction value?

Perhaps if the response has to be an integer 65000 then truncate or typecast to Integer...

Enjoy!

------------------------------
Jean-Claude Chami
SIA Innovations Inc.

------------------------------