need help porting function to C

I worked on the function a bit but it didnt work yet, what i did


uint32_t temp;

// b = 3963                                 'Bwert vom NTC
// Ts = 333.15                              'Bezugstemperatur in Kelvin 
hier 60°C
// rs = 221                                 'Widerstand bei 
Bezugstemperatur TS
analog = adcwert(i);
temp =((3963 * 333.15) / ((333.15 * (log(((((0.0047898 * analog) * 1242) 
/ (4.9 - (0.0047898 * analog))) / 221)))) + 3963)) - 273.15;
sendUSART(temp);

but i get the wrong data, mhh

Danke,wunderbar das deckt sich fein mit meinen 61,39

libm.a hab ich drin, aner wenn ich das nun über usart schicken möchte 
meckert der compiler rum

sendUSART(temp);

../measure.c:158: error: incompatible type for argument 1 of 'sendUSART'

muss ich das vorher noch wandeln ?

Works like a Charm now, just one Problem i still have is that i need the 
resulting value temp converted to single hex values.

Meaning if a Temperature result would be 12.9 i want to have a result of

seg0 = 1
seg1 = 2
seg2 = 9

i tried with

  dtostrf(temp,3,1,ascii);sendUSART(ascii); sendUSART("\r\n");

  if ( temp > 10 )
{
        strncpy(seg0, ascii , 1);
  strncpy(seg1, ascii +1, 1);
  strncpy(seg2, ascii +3, 1);
}

but since this still results the ascii values
(seg0 ="1",seg1 ="2" and seg2 ="9")
, how do i convert them to hex codes ?

Thanks in Advance

Tried that before already, but i stll need to convert the Value since 
the Compiler gives me

error: lvalue required as increment operand

Since i needed to define my seg0 to seg9 values as char i cant add '0'