Performing calculations with variables

Forum 2005-2010 (read only) Software Syntax & Programs
1

float Csp=0;
float C1=0;
float C2=0;
float G=0;
float OF=0;
float m=0;
float X=0;
float X1=0;
float FR=0;
float t=0;
float t1=0;
float val=0;
float val1=0;
float val2=0;
float analogPin=3;
float C3=0;

void setup() {
Serial.begin(9600);
pinMode(1,OUTPUT);
pinMode(4, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(3, OUTPUT);
Serial.print(12, BYTE);
Serial.print(129,BYTE);
Serial.print("LCL");
Serial.print(148,BYTE);
Serial.print("0.09");
Serial.print(136,BYTE);
Serial.print("SP");
Serial.print(155, BYTE);
Serial.print("0.1");
Serial.print(143, BYTE);
Serial.print("UCL");
Serial.print(162, BYTE);
Serial.print("0.11");
Serial.print(188, BYTE);
Serial.print("Salty");
Serial.print(194, BYTE);
Serial.print(203, BYTE);
Serial.print("DI");
Serial.print(22,BYTE);
}

void loop(){
digitalWrite(4, HIGH);
delay(1000);
float (val=0);
float (val2=0);
float (val1=0);
float (Csp=0);
float (C1=0);
float (G=0);
float (C2=0);
float (X=0);
float (X1=0);
float (m=0);
float (OF=0);
float (t=0);
float (FR=0);
float (t1=0);
float (t=0);
float (m=0);
float (C3=0);
digitalWrite(4, LOW);
val=(analogRead(analogPin));
m=79.1;
FR=9.25;
OF=.15;
Csp=.1;
C1=((.0006*(pow(val,.8133))));
G=.7;
C2=(C1+(Csp-C1)G);
C3=(C1-(Csp-C1)G);
X=((m(C2-C1))/((1-OF)(.01-C1)));
X1=((m*(C1-C3))/((1-OF)(C1)));
t=((60(X/FR))1000);
t1=((60(X1/FR))1000);
val2=(pow(val, .8133).0006);
Serial.print(174, BYTE);
Serial.print(val2,4);
delay(1000);
if (val2<.09){
digitalWrite(7, HIGH);
delay(t);
digitalWrite(7, LOW);
Serial.print(169, BYTE);
Serial.print("ON");
Serial.print(182, BYTE);
Serial.print("OFF");
delay(8500);
}
if (val2>.11){
digitalWrite(8, HIGH);
delay(t1);
digitalWrite(8, LOW);
Serial.print(182, BYTE);
Serial.print("ON");
Serial.print(169, BYTE);
Serial.print("OFF");
delay(8500);
}

}

This is my code. It's supposed to control the salinity of water in a tank, but val2 is showing up as 0. val2 is the variable I used for % weight of salt in the water. val is the analog value from the conductivity sensor. The equation I used (.0006(val)^.8133) comes from a calculation in excel. Did I enter that equation wrong? Do I have to do something else in order to used the pow() function? Help please.

2

All floats should be initialized as 0.0 and not 0.

3

Have you confirmed that the analog sensor works?

float analogPin=3;

...using a float for a pin number is a bad idea. Change the declaration to this...

const int analogPin=3;

4

@ Senso: by an amazing ( four billion to one!) coincidence of IEEE 754 excess 127 floating point , the integer and float representations of zero are identical right down to the bit level, and better still, are also completely endian-agnostic.

Anyway, all those global floats would have been initialised to zero, even if they had not been explicitly assigned the value.

Oh yeah, and what Coding Badly said, with a side-order of using the # icon when posting code.

5

I have worked with a strange PIC compiler that spited out all sorts of errors if all floats where not initialized to 0.0 0 wont cut it for some reason.

6

Yet another reason to be grateful we're not using PICs.
:smiley: