source: sasview/src/sas/plottools/transform.py @ e46cbc5

import math
         
         
def toX(x, y=None):
    """
    This function is used to load value on Plottable.View
    
    :param x: Float value
    
    :return: x
    
    """
    return x


def toX_pos(x, y=None):
    """
    This function is used to load value on Plottable.View
    
    :param x: Float value
    
    :return: x
    
    """
    if not x > 0:
        raise ValueError, "Transformation only accepts positive values."
    else:
        return x


def toX2(x, y=None):
    """
    This function is used to load value on Plottable.View
    
    Calculate x^(2)
    
    :param x: float value
    
    """
    return x * x


def fromX2(x, y=None):
    """
    This function is used to load value on Plottable.View
    Calculate square root of x
     
    :param x: float value
     
    """
    if not x >= 0:
        raise ValueError, "square root of a negative value "
    else:
        return math.sqrt(x)


def toX4(x, y=None):
    """
    This function is used to load value on Plottable.View
    
    Calculate x^(4)
    
    :param x: float value
    
    """
    return x * x * x * x


def fromX4(x, y=None):
    """
    This function is used to load value on Plottable.View
    Calculate square root of x
     
    :param x: float value
     
    """
    if not x >= 0:
        raise ValueError, "double square root of a negative value "
    else:
        return math.sqrt(math.sqrt(x))
         

def toLogX(x, y=None):
    """
    This function is used to load value on Plottable.View
    calculate log x
    
    :param x: float value
    
    """
    if not x > 0:
        raise ValueError, "Log(x)of a negative value "
    else:
        return math.log(x)
    
def toOneOverX(x, y=None):
    """
    """
    if x != 0:
        return 1/x
    else:
        raise ValueError, "cannot divide by zero"
    
    
def toOneOverSqrtX(y, x=None):
    """
    """
    if y > 0:
        return 1/math.sqrt(y)
    else:
        raise ValueError, "transform.toOneOverSqrtX: cannot be computed"
    
    
def toLogYX2(y, x):
    """
    """
    if (y * (x**2)) > 0:
        return math.log(y * (x**2))
    else:
        raise ValueError, "transform.toLogYX2: cannot be computed"
     
     
def toLogYX4(y, x):
    """
    """
    if (math.pow(x, 4) * y) > 0:
        return math.log(math.pow(x,4) * y)
    else:
        raise ValueError,"transform.toLogYX4: input error"
     
     
def toYX4(y, x):
    """
    """
    return math.pow(x, 4) * y

def toYX2(y, x):
    """
    """
    return math.pow(x, 2) * y

def toLogXY(y, x):
    """
    This function is used to load value on Plottable.View
    calculate log x
    
    :param x: float value
    
    """
    if not (x * y) > 0:
        raise ValueError, "Log(X*Y)of a negative value "
    else:
        return math.log(x * y)


def errToX(x, y=None, dx=None, dy=None):
    """
    calculate error of x**2
    
    :param x: float value
    :param dx: float value
    
    """
    if dx == None:
        dx = 0
    return dx


def errToX_pos(x, y=None, dx=None, dy=None):
    """
    calculate error of x**2
    
    :param x: float value
    :param dx: float value
    
    """
    if dx == None:
        dx = 0
    return dx


def errToX2(x, y=None, dx=None, dy=None):
    """
    calculate error of x**2
    
    :param x: float value
    :param dx: float value
    
    """
    if  dx != None:
        err = 2 * x * dx
        return math.fabs(err)
    else:
        return 0.0
    
    
def errFromX2(x, y=None, dx=None, dy=None):
    """
    calculate error of sqrt(x)
    
    :param x: float value
    :param dx: float value
    
    """
    if (x > 0):
        if(dx != None):
            err = dx / (2 * math.sqrt(x))
        else:
            err = 0
        return math.fabs(err)
    else:
        msg = "transform.errFromX2: can't compute error of negative x"
        raise ValueError, msg


def errToX4(x, y=None, dx=None, dy=None):
    """
    calculate error of x**4
    
    :param x: float value
    :param dx: float value
    
    """
    if  dx != None:
        err = 4 * math.pow(x, 3) * dx
        return math.fabs(err)
    else:
        return 0.0
    
    
def errFromX4(x, y=None, dx=None, dy=None):
    """
    calculate error of x^1/4
    
    :param x: float value
    :param dx: float value
    
    """
    if (x > 0):
        if(dx != None):
            err = dx / (4 * math.pow(x, 3/4))
        else:
            err = 0
        return math.fabs(err)
    else:
        msg = "transform.errFromX4: can't compute error of negative x"
        raise ValueError, msg
 
 
def errToLog10X(x, y=None, dx=None, dy=None):
    """
    calculate error of Log(x)
    
    :param x: float value
    :param dx: float value
    
    """
    if dx == None:
        dx = 0
        
    # Check that the point on the graph is positive
    # within errors
    if not (x - dx) > 0:
        msg = "Transformation does not accept"
        msg += " point that are consistent with zero."
        raise ValueError, msg
    if x != 0:
        dx = dx / (x * math.log(10))
    else:
        raise ValueError, "errToLogX: divide by zero"
    return dx
    
    
def errToLogX(x, y=None, dx=None, dy=None):
    """
    calculate error of Log(x)
    
    :param x: float value
    :param dx: float value
    
    """
    if dx == None:
        dx = 0
            
    # Check that the x point on the graph is zero
    if x != 0:
        dx = dx/x
    else:
        raise ValueError, "errToLogX: divide by zero"
    return dx


def errToYX2(x, y, dx=None, dy=None):
    """
    """
    if dx == None:
        dx = 0
    if dy == None:
        dy = 0
    err = math.sqrt((2 * x * y * dx)**2 + ((x**2) * dy)**2)
    return err
    
    
def errToLogXY(x, y, dx=None, dy=None):
    """
    calculate error of Log(xy)
    
    """
    # Check that the point on the graph is positive
    # within errors
    if (not (x - dx) > 0) or (not (y - dy) > 0):
        msg = "Transformation does not accept point "
        msg += " that are consistent with zero."
        raise ValueError, msg
    if (x != 0) and (y != 0):
        if dx == None:
            dx = 0
        if dy == None:
            dy = 0
        err = (dx/x)**2 + (dy/y)**2
    else:
        raise ValueError, "cannot compute this error"
   
    return math.sqrt(math.fabs(err))
    
    
def errToLogYX2(x, y, dx=None, dy=None):
    """
    calculate error of Log(yx**2)
    
    """
    # Check that the point on the graph is positive
    # within errors
    if (not (x - dx) > 0) or (not (y - dy) > 0):
        msg = "Transformation does not accept point"
        msg += " that are consistent with zero."
        raise ValueError, msg
    if (x > 0) and (y > 0):
        if (dx == None):
            dx = 0
        if (dy == None):
            dy = 0
        err = (2.0*dx/x)**2 + (dy/y)**2
    else:
        raise ValueError, "cannot compute this error"
    return math.sqrt(math.fabs(err))
        
        
def errOneOverX(x, y=None, dx=None, dy=None):
    """
    calculate error on 1/x
    
    """
    if (x != 0):
        if dx == None:
            dx = 0
        err = dx/x**2
    else:
        raise ValueError, "Cannot compute this error"
    return math.fabs(err)


def errOneOverSqrtX(x, y=None, dx=None, dy=None):
    """
    Calculate error on 1/sqrt(x)
    
    """
    if (x > 0):
        if dx == None:
            dx = 0
        err = -1/2*math.pow(x, -3.0/2.0) * dx
    else:
        raise ValueError, "Cannot compute this error"
    return math.fabs(err)


def errToLogYX4(x, y=None, dx=None, dy=None):
    """
    error for ln(y*x^(4))
    
    :param x: float value
    
    """
    # Check that the point on the graph is positive
    # within errors
    if (not (x - dx) > 0) or (not (y - dy) > 0):
        msg = "Transformation does not accept point "
        msg += " that are consistent with zero."
        raise ValueError, msg
    if dx == None:
        dx = 0
    if dy == None:
        dy = 0
    err = math.sqrt((4.0 * dx/x)**2  + (dy/y)**2)
    return err


def errToYX4(x, y=None, dx=None, dy=None):
    """
    error for (y*x^(4))
    
    :param x: float value
    
    """
    # Check that the point on the graph is positive
    # within errors

    if dx == None:
        dx = 0
    if dy == None:
        dy = 0
    err = math.sqrt((dy * pow(x, 4))**2  + (4 * y * dx * math.pow(x, 3))**2)
    return err